Dorothy Sladden (1907-1937): Ernest W. MacBride, Evolution and Eugenics. Part 2. Frogs’ eggs, sports and monstrosities

As well as for the inheritance of acquired characters, MacBride was also looking for environmental factors that caused mutations, in order, it seems, to provide an explanation for the findings of the Mendelian geneticists. The basis is explained by the opening paragraph of his article, The work of Tornier as affording a possible explanation of the causes of mutations, written in 1924 for Eugenics Review (15, 545-555):

Gustav
Tornier

In a previous communication to the Society I gave an outline of recent discoveries which tended to show that the effects of habits acquired during the lifetime of the individual were transmitted to posterity. Since that time more and more evidence pointing in the same direction has come in, and finally the recent experiments of Pavlov may be regarded as decisive on the question. The inheritance of environmental effect is therefore a vera causa, and has probably been the chief, if not the only cause, of the evolution of the plant and animal kingdoms, but it is certainly not the only cause of variation. The conspicuous deviations from the normal, known as sports or monstrosities, which appear suddenly, which are inherited strongly, and which "mendelize" when crossed with the type, still demand an explanation of the cause of their occurrence. It is on characters such as these that the breeder seizes when he wishes to produce a new strain; and it is the offspring of similar "sports" in the human race that fill the slums of our great cities.

     To say that these sports owe their origin to "mutations" in the chromosome-complex of the type is merely playing with the question; it is, in the words of Darwin, to substitute a form of words for an explanation. Granted that if the hereditary potentiality of a stock is changed, the nuclei of the germ cells have undergone a change; to assert this is merely to push the difficulty one step further back. What has changed the nuclei? Till we can answer that question all talk of an explanation of mutations is futile.

     …In view of these facts it occurred to Gustav Tornier [1858-1938; he worked in Berlin] that there must be some general underlying cause for the production of these abnormalities. It seemed to him futile to attribute each one to the separate appearance by chance of a '*factor." He was thus led to formulate what Milewski calls an “epoch-making theory” to the confirmation of which Milewski has himself largely contributed. Like the Mendelian theory itself the Tornierian hypothesis did not at first attract the notice to which it was entitled. This was due to two causes—first because the theory conflicts with all preconceived ideas as to the origin of mutations, and secondly because Tornier has published his results for the most part in journals which have not a sufficiently wide circulation to reach zoologists in general. Tornier's theory is as follows:—Every embryo is endowed at the beginning of its existence with a certain quantity of protoplasmic energy. This energy manifests itself in two ways: (1) by the early beginning and vigorous character of the movements of the embryo; (2) by the ability of the embryo to resist the tendency of all its tissues, especially those of a less active growth, to absorb an excess of water—in a word to regulate the intake of water. In practically all eggs the portion of less active growth is that in which the yolk globules are stored, and hence Tornier speaks rather too loosely of an absorption of water by "the yolk" and its consequent swelling. The swelling is not confined to yolk-containing cells, nor strictly speaking is it the yolk itself which swells, since this consists chiefly of globules of a lecithin-like substance insoluble in water. The very same swelling takes place in mammalian embryos in which there is no yolk. Davenport and Parker showed long ago that a large part of the increase in bulk which embryos undergo during the earlier period of their development is due to the imbibition of water.

     Now according to Tornier, when an embryo is exposed in the earliest period of existence to scarcity of oxygen, the protoplasm becomes weakened and is not able to prevent the overswelling of the less active portions of the body by water. This abnormal swelling— since the embryo is confined within a relatively inextensible membrane—leads to pressure on the actively growing parts which impedes their growth, distorts their shape, and in extreme cases, prevents their growth altogether. If we examine in detail its effects in goldfish embryos we find that all the natural cavities of the body, such as the buccal cavity, the gill cavity (beneath the operculum), and the body cavity become enlarged beyond their natural sizes, whilst strong pressure is exerted by the swollen yolk-sac against the growing embryo in an antero-posterior direction, so as to impede the natural tendency of the embryo to grow in length.

     …The interest in all studies of heredity to the Eugenics Education Society is, of course, their   applicability to human conditions.

     Tornier's work suggests strongly that bad conditions during the period of conception and the early phases of development may be the original cause of the degenerative mutants in man, including under that head not only mental defect, but haemophilia, night-blindness, colour-blindness, &c. But the important fact is that, however caused, the plasma-weakness is handed on to posterity. It is the object of negative eugenics to prevent these plasma-weak stocks from adding their quota to the race, by discouraging their reproduction. In the future we may hope that eugenics, in conjunction with medical research, may perhaps detect and isolate the specific causes of plasma-weakness, and thus diminish, if not entirely prevent, the appearance of plasma-weakness in the race.

It is difficult, when looked at from 2015, to believe that this was written by anything other than a crank. It is also difficult to believe, again when looked at from 2015, that the work in the first two papers, on the development of frog embryos after an environmental insult, were other than fanciful and difficult to not believe that they were thought as fanciful at the time by those not involved directly with MacBride. The introduction to Dorothy Sladden’s first paper summarises the thoughts of Tornier as expressed in MacBride’s article and explains the line of reasoning for the experiments she did:

In 1908, Tornier published a paper on the probable causes of the formation of the abnormal "fancy" races of goldfish. All these races originated in China where the wild ancestor (Carausius [sic] auratus*) still abounds in the streams, It had been supposed that these races were produced by a secret process known only to the Chinese breeders. The fish during winter were kept crowded in earthenware pots, on shelves in dark and insanitary huts; in summer they were transferred to small and filthy tanks overgrown with weeds. In these tanks they spawned and much of the spawn perished; amongst the fraction which survived, however, all sorts of abnormalities were found. By selecting the most striking of these, the breeders secured the parents of their “fancy" breeds, which showed in every succeeding generation a strong tendency to revert to the normal; only by the most rigid selection was anything like a "pure" race obtained.

    Tomier drew the conclusion that, the abnormalities were due to the effects of lack of oxygen in very early stages of development. This lack induced what he called "plasma-weakness" in different parts of the formative area of the very young embryo. In consequence of these localised areas of weakness the protoplasmic part of the egg was liable to mechanical distortion, induced by abnormal pressure from the yolk ; the latter absorbed water and swelled, thus crushing and destroying the protoplasmic structures from which the future organs of the adult arc formed.

The practicalities of the initial experiments involved keeping frog eggs in a 10% sucrose solution for four hours and seeing how the eggs and tadpoles developed. the sucrose solution was used in the belief—as in Tornier’s experiments outlined in MacBride’s article—that it would reduce the concentration of oxygen in the water sufficiently to affect the developing embryo. This is the summary of that paper:

Eggs of Rana temporaria were exposed, at the end of segmentation, 24 hours after fertilisation, to a 10 per cent, solution of sugar in tap-water for 4 hours; they were then transferred to normal aerated water. The resulting larvae exhibited marked structural abnormalities, although these might not be obvious for a prolonged period, e.g., 3 to 4 months after fertilisation. These abnormalities have, been described as (a) distention of body-cavity; (b) rupture of gut and extrusion of yolk; (c) flexure of tail; (d) distortion of sacral region; (e) non-appearance of limb.

However, in the second paper it was realised that the effect of immersion in sucrose was probably caused by an osmotic effect rather than lack of oxygen (I calculate the oxygen concentration in the water would have been reduced by only 9%):

Summarising these somewhat inconclusive results, it would seem that the effect of sugar is not the removal of oxygen as previously assumed, but very possibly osmotic action and is responsible for the early abnormalities in particular, while pH decrease may be responsible for the later ones…It now seems possible, however, that overcrowding may have seriously affected all the previous results.

The experiments show nothing other than when frogs’ eggs are damaged, the tadpoles do not develop normally, although I am sure that MacBride really fancied the notion that dirty conditions lead to ‘mutations’ (as proposed by Tornier for the genesis of the domestic strains of fancy goldfish) which are then embedded forever in the working class unless expunged by negative eugenics, and that is the reason why the newly-graduated Miss Sladden was given the project.

Dorothy Sladden’s skills in rearing frogs through metamorphosis are evident and were obviously put to good use by others in in the department. For example, Peter Gray in a paper on development of the development of the amphibian kidney also published, like her first paper, in 1930, thanks her profusely: ‘indeed, it is to her skill in the rearing of animals under artificial conditions that I am indebted for the greater part of my material.”

The studies described here have nothing of importance that I can see. By contrast the next set of experiments she did produced biologically significant results and should be seen in a different light to those on frogs' eggs. I will deal with them in my next post, Part 3.

View image | gettyimages.com

The two papers are:

Sladden, D.E. 1930. Experimental distortion of development in amphibian tadpoles. Proceedings of the Royal Society B 106, 318-325

Sladden, D.E. 1932. Experimental distortion of development in amphibian tadpoles. Part II. Proceedings of the Royal Society B 112, 1-12

*She was confusing the name of the goldfish (Carassius auratus) with the organism she wroekd on next, the stick insect (Carausius morosus)

Dorothy Sladden (1907-1937): Ernest W. MacBride, Evolution and Eugenics. Part 1

This is a sad story. It is also a much longer story than I thought at the outset and several posts will be needed to cover it; this is the first.

On 25 January on my other site dealing with the history of keeping reptiles and amphibians I noted that I had found a short series of articles on fishes, reptiles and amphibians at London Zoo in volume 2 of Water Life magazine published in 1937, written by a Miss D.E. Sladden, and that the final issue of the volume contained the news that Miss Sladden D.I.C., C.M.Z.S. had died as the result of a road accident. The report in Water Life continued:

She had been engaged in research work at the London Zoological Gardens, and was particularly interested in tropical fish. Shortly before she died, she finished a paper on breeding Angel Fish, which gives fuller details than any previously written on this subject, and is a valuable contribution to fish-keeping knowledge…

I then found that Dorothy Ena Sladden of The Poplars,  2 Somerset Road, Brentford, Middlesex died on 27 June 1937, aged 29, in Hounslow Hospital, leaving £858.4s.11d. At that stage I could not find a record of her birth in England or an entry in the 1911 Census. This, together with the fact that she was described by Water Life as a C.M.Z.S. (Corresponding Member of the Zoological Society of London) suggested to me that she was born overseas and came back to Britain. However this was not the case since by searching for the person granted administration of her estate, Edward Cuthbert Sladden, tailor and outfitter, I found in the 1911 Census an Edward Sladden, Gents outfitter with a daughter, Dorothy, living at 17 Clifden Road, Brentford, Middlesex. From there it was easy to determine that Dorothy Sladden was born in the fourth quarter of 1907 in the Dartford Registration District of Kent, the daughter of Edward Cuthbert and Annie Isabella (née Oudney). I cannot find the birth of any siblings. One child of the marriage (five years earlier) is recorded in the 1911 Census. After 1912, the mother’s surname was recorded in the registers and there are no Sladden births recorded with an Oudney as mother.

Dorothy Sladden’s mother died on 9 February 1939, aged 62; her father died on 13 November 1961, aged 83, leaving £8784; probate was granted to Barclays Bank as executors of his will.

I looked up the additional genealogical details because I came across an intriguing item in the minutes of the Council of the Zoological Society when I was searching for information on Burgess Barnett. At the meeting on 21 July 1937, Council noted with regret the death of Miss Sladden and passed condolences to her parents. But Professor E.W. MacBride then said that Miss Sladden had been working on Proteus and that it was important that a replacement be recruited to carry on the work. At this time MacBride had taken up the cudgels on behalf of Burgess Barnett and was attempting to get him reinstated as Curator of Reptiles.

Proteus could only refer to Proteus anguinus, the Olm, Knowing that MacBride was a Lamarckian supporter of Kammerer and his memory and that Kammerer had worked on P. anguinus as well as on the Midwife Toad, Alytes obstetricans, I guessed that Miss Sladden was working on an attempt to replicate Kammerer’s experiments and that she was some way working with MacBride. A Google search linking Sladden with MacBride came up trumps. Before describing the work she did, it is worth considering the state of evolutionary theory and research in the early decades of the 20th Century, especially in Britain.

While evolution was on firm ground, natural selection was not. With hindsight—and this area has been covered extensively by historians, often not that well—progress was blocked by individuals in positions of power and influence defending fixed positions to the bitter end and refusing to accept that evidence could come from the emerging field of genetics; equally the geneticists were split between those who could envisage evolution occurring gradually or in sudden steps. Not until the ‘modern synthesis’ (the term invented by Julian Huxley in his book of 1942) was it realised that Darwin, Mendel and the advances in population genetics could be brought under the one all-embracing concept of how evolution happens.

Ernest William MacBride FRS was from 1913 until he retired in 1934, Professor of Zoology at Imperial College, occupying T.H. Huxley’s old chair. I am using Imperial College here as a convenience because papers from his department give the Royal College of Science as the address. The Royal College of Science was a constituent of Imperial College from 1907.

E.W. MacBride

MacBride not only defended Lamarckian evolution; he used his interpretation of it to promote extreme eugenic views. The picture that emerges is of a publicly combative but personally supportive individual. This is what Lancelot Hogben FRS (1895-1975) had to say about him (Lancelot Hogben. Scientific Humanist, edited by Adrian and Anne Hogben, Merlin Press, 1998):

While I was at Imperial College, the head of my department was Professor E. W MacBride. He had long since passed from the dynamic to the prostatic phase of the life cycle of a professional man. Till the beginning of World War I, he had carried out research on the embryonic development of sea urchins, starfishes and other marine forms. In the course of the war, he had relapsed into mental hibernation during the colder part of the year and aestivation during the warmer half. By birth he was an Ulsterman, and in a precocious dotage, he had exchanged the Calvinism of his forefathers for eugenics and had become a pillar of the Eugenics Society. This was a circus of snobs and racist cranks.

     In my first term at Imperial College, MacBride invited me to attend a lecture he gave on behalf of the Society. To improve the race, he urged on his audience the desirability of legislation to make sterilisation by vasectomy obligatory for males earning less than £400 a year. At that date my own modest salary was £350 and I had already committed paternity—and quite legitimately. On the whole though we got on well together. My output of published work from his department was prolific. It gave him something new to talk about at lunch in the Athenaeum Club, one of the geriatric wards of the Establishment.

Hogben omits to mention, by the way, that the ranks of the Eugenics Society were filled by men of the left as well as those of the right.

William Thomas Calman FRS (1871-1952) wrote MacBride’s obituary notice for the Royal Society. Unlike the many hagiographic efforts characteristic of the time, Calman clearly tried to achieve a balanced view:

Already, in a paper published in 1895 on 'Sedgwick's theory of the embryonic phase of Ontogeny as an aid to phylogenetic theory', MacBride had declared his adhesion to Lamarck's views on the causation of evolution—changes in the environment of organisms leading to changes in habits, and these, in turn, through the inherited effects of use and disuse, to changes of structure. In later years, the support of the Lamarckian theory became one of the dominant interests in his life. He championed it unceasingly, uncompromisingly. and, it must he confessed, sometimes uncritically, and expounded with characteristic vigour what he believed to be its social implications. He welcomed with an interest that came dangerously neat credulity any experimental results tending to demonstrate inheritance of impressed modifications, brushing aside as irrelevant the objection that ‘the more unequivocal the experiments devised to demonstrate its reality the more clearly do they show it to be of so fugitive a kind as to have no significance in evolution'. He also glossed over what still seem to some the chief flaws in the Lamarckian theory, the very limited structural changes that can he produced by use and disuse and the fact that they do not seem to be, of necessity, adaptive  in  nature. But, as sometimes  happens with ardent controversialists, he was much less extreme in private conversations than when writing or on the platform. And, after all, over-statement is not confined lo the defenders of Lamarckism. Has it not been stigmatized as 'a doctrine supported by far less positive evidence than exists for the reality of witchcraft’?

     There is no space here, neither is there any need, to do more than mention the many diverse fields other than zoology over which MacBride's activities extended, philosophy, sociology, eugenics, even theology. Sometimes, it is to he feared, he ventured into regions where his reach exceeded his grasp. He had the type of mind that can never rest content with the narrow outlook of the specialist but must always try to see even the larva of a starfish in its relation to the universe. It is an attitude that will never be understood by those biologists, be they systematists or geneticists or what not, who arc content to spend happy and laborious lives exploring the details of their specialities and are 'not interested in evolution'. Even the champions of lost causes and forsaken beliefs fulfil a useful function if they keep youth from forgetting that there are some questions on which the last word has still to be said.

In an earlier paragraph Calman writes of MacBride’s style of management:

One distinguished pupil who has had unusually wide experience writes; 'MacBride was a most admirable director of a research department and took a greater personal interest in the work of his students than any professor I have ever known—although, in practice it was sometimes a little wearing, as I felt that one was expected to have spectacular results to report every morning at 11.30 a.m. However, MacBride cultivated a most friendly atmosphere in which all the research students were interested in each other's work and were ready to discuss it and to give and receive help all round in a way that I have not met with anywhere else.' One who served under him as a lecturer says: 'One thing that can be said about MacBride is that he was an ideal chief. Even those of his subordinates, who like myself disagreed most strongly with his ideas always entertained the most sincere appreciation of his kindness and consideration in that capacity.’

My guess is that the lecturer referred to by Calman was Harold Munro Fox FRS (1889-1967). In his biographical memoir, Sir James Eric Smith FRS (1909-1990) wrote:

In 1913 when Fox was a lecturer at the Royal College of Science he brought to Professor MacBride’s notice the work of Paul Kammerer which purported to show from his experiments on salamanders, frogs and the ascidian Ciona that characters acquired in response to the environmental conditions in which they were kept or as a result of certain kinds of operative treatment were transmitted to their offspring. MacBride's stubborn advocacy of the inheritance of acquired characters is well remembered, and he was not disposed to think well of young men who strongly opposed his views on the subject. It says much for Fox's courage therefore that, while still in MacBride's department, he drew attention to the essential weakness of Kammerer's experiments which had taken little account of the need to rear the offspring under conditions which eliminated the possibility of their acquiring their characteristics as environmental adaptations in the same way as had their parents. After the war Fox repeated Kammerer's experiments on Ciona. This involved the amputation of the branchial siphons, after which (Kammerer had said) the siphons regenerate to a greater length, the animals thereafter transmitting this change to their offspring. Fox showed, however, that if the animals were kept in similar culture conditions before and after the amputation of the siphons there was no increase in length of the regenerated structures. However, an increase in the food supply induced the growth of long siphons and this happened both in siphon-amputated and in uninjured animals.

MacBride is still remembered for his opposition to the then new science of genetics. The history of the John Innes Centre notes the founding of the Journal of Genetics by William Bateson FRS (1861-1926) who also coined the word genetics:

The Journal was an important focus for British geneticists who faced powerful opposition from EW MacBride, Professor of Zoology at Imperial College, London, and a member of the governing body of John Innes (from 1919)[Bateson was its first Director] and Karl Pearson, Professor of Applied Mathematics and Mechanics at University College. ‘They stood at the entrance of the Royal Society like the leographs which guard the portals of a Burmese Buddhist temple’ (Crew, 1969).

Bateson was a leading opponent of Paul Kammerer and had been present at a private meeting with Kammerer in 1923. Cock and Forsdyke in their book, Treasure Your Exceptions: The Science and Life of William Bateson (Springer, 2008) wrote:

H Graham Cannon wrote in 1959 that there had been a private meeting in MacBride’s room at the Royal College of Science, with just four people present: MacBride, Kammerer, Cannon and Bateson. Kammerer produced his Alytes [Midwife Toad] specimen in a glass tube and MacBride examined it “literally for a couple of seconds” (those who are already converts are easily convinced!) before passing it on to Cannon, and in turn to Bateson, who examined it with a hand-lens. Cannon then alleges that Bateson then said to him, sotto voce “It looks to me like a spot of black ink.” If this is correct, then Bateson’s comment showed a quite remarkable prescience, for three years later the nuptial pad on the same specimen was shown to have been injected with Indian ink. However, it seems likely that this part of Cannon’s account owes more to his own creative hindsight than to Bateson’s prophetic powers.

I do not know how Cock and Forsdyke came to make the last comment. Herbert Graham Cannon FRS (1897-1963), in MacBride’s department in 1923, much later turned to re-interpreting Lamarck’s work, also believing the ‘modern synthesis’ based on Mendelian genetics was an inadequate explanation for evolution and that a correctly interpreted account of what Lamarck actually said—which I think in modern terms would be extreme phenotypic plasticity rather than inheritance of acquired characters—was more likely, with characters appearing in any generation to respond to a change in environment.

The 1920s and 1930s saw MacBride fiercely defending Lamarckism but also looking for evidence of the sort that he thought Kammerer had obtained for the inheritance of acquired characteristics.

That is where Dorothy Sladden came into the picture. She seems to have worked for and/or under MacBride since 1928 (when she would have graduated at the age of 21). At some time before 1933 she was awarded the Diploma of Imperial College (D.I.C.), a qualification approximately equivalent to that of a Master’s by research.

Lamarckists like MacBride would interpret any environmentally-induced change in the adult which appeared in the offspring, however small, as evidence in their favour. And this is where some of the experiments done, dismissed or ignored by the Neo-Darwinians, become interesting. The distinction could not, or was not, then be drawn between the inheritance of an acquired characteristic by alterations in the genome (the Lamarckian interpretation) or by non-genomic, or epigenetic mechanisms. Only in the past twenty years has the extent of epigenetic inheritance become well known and indeed fashionable, largely, I would argue because of David Barker’s work indicating, from historical human epidemiological evidence, the relation of differences in fetal growth to differences in the incidence of diseases in later life. The evidence for maternal, intergenerational effects in plants and animals had been accumulating for decades and had really been brought to more general notice by the work of plant and animal breeders—the quantitative geneticists—who needed to distinguish between the effects of genes and the non-genetic effects that were interfering with their experiments. Some acquired characteristics were inherited but not through the genes.

But in the 1930s, any putative demonstration of a maternal effect—‘where the phenotype of an organism is determined not only by the environment it experiences and its genotype, but also by the environment and genotype of its mother’—would be seized on by the Lamarckists as evidence in their favour but dismissed by the Darwinians as irrelevant or simply wrong. That adaptive maternal effects, where mothers sense environmental conditions and transmit signals to their offspring through materials in their eggs or through the placenta or through milk in order to enable them to adapt more quickly to the environmental conditions in which they are born or hatched would be discovered, for example, or through affecting the activity but not the underlying DNA sequence, would simply have been beyond the ken of either faction at the time.

So it was work on alterations in the environment that brought about changes in the offspring that Dorothy Sladden was looking for. I found five papers by Dorothy Sladden on work she had done in MacBride’s department at Imperial College from 1928 when she would have been 21, before moving to the Zoo, I presume in 1936. It is clear from the papers that the original and general ideas for the experiments were generated by MacBride. This is what she had to say on one of her papers on frogs’ eggs:

I would like to express my deep gratitude to Prof. E. W. MacBride not only for the great encouragement and assistance which he has given me, while I have been working under his supervision, but also for his original suggestion that this line of research could be profitably followed.

In Part Two of this long story, I will consider the first topic of Dorothy Sladden’s research.