August i6, 191 7] 



NATURE 



495 



The suggestion has been made that the moon may 

 not be a perfectly rigid body, but may have sensible 

 change of shape under the varying strains ; also that 

 the interior may be partly fluid; the final chapter of 

 the memoir discusses the changes in the equations 

 of motion to which these hypotheses gi\'fe rise, but 

 does not express any opinion as to their tenability. 

 The preceding chapter gives the numerical calculation 

 of a large number of coefficients, using Brown's ex- 

 pressions for the moon's co-ordinates, and different 

 assumptions for the values of fe,, fej, fej. 



A. C. D. C. 



T' 



ADAPTATION AND DISEASE.' 

 HE time has come to bring before biologists in 

 general the contributions of medical research 

 of the last quarter of a century to the study of 

 evolution. The fact of evolution all thinking .minds 

 accept, but as to how evolution has been, and is 

 being, brought about is a very different matter. The 

 fight truly centres upon the cause or causes of varia- 

 tion — whether the tendency to vary is something in- 

 herent in living matter, numerous variations present- 

 ing themselves through this inherent tendency, of 

 which those that are best fitted for their environment 

 alone survive, or whether it is primarily and essentially 

 brought about by forces acting from without upon a 

 relatively labile living matter : whether, that is, varia- 

 tion is inherent, proceeding from within, or acquired, 

 proceeding from without. 



But this basal problem has been largely neglected 

 by the biologists, the fight all these years waging 

 round the secondary problem of the transmission of 

 acquired properties to the offspring. Herbert Spencer 

 made this transmission of acquirements one of his 

 '"principles." Weismann violently- opposed the doc- 

 trine, carrying with him latter-day biologists, until 

 Mr. Bateson, replete with his studies upon Mendelism, 

 reaches the antipodal suggestion that when a new 

 prop)erty manifests itself in any individual of any 

 species, it is impossible to regard it as an acquire- 

 ment : it is not new, but its manifestation is due to 

 loss of properties already possessed. Evolution, like 

 a squid, progresses backwards, what appears to be 

 a new property is on the contrary primeval. Prof. 

 Bateson 's address on Heredity at the International 

 Medical Congress' in London in'1913, and his Presi- 

 dential address at Melbourne in 19 14, were quoted in 

 extenso. That which to outward seeming is the 

 simplest form of life is verily in constitution the most 

 marvellously comjilex : the higher forms of life are 

 the lower. " ^ 



The truth seemed to be that valuable and fascinating 

 as are the studies for the establishment and amplifica- 

 tion of Mendel's law, that law deals only with the 

 interplav of allelomorphs, with the combinations and 

 permutations of positive and negative unit properties 

 possessed by the species. It only establishes the 

 extent of variation possible within the hotindaries of 

 the species. But no amount of interplay of properties 

 alreadv possessed by the species will result in the 

 production of individuals which are outside the species. 



Sir Ray Lankester recently laid down that the one 

 fallacy in all Lamarckian doctrine was that adopted 

 by Herbert Spencer, namely, what hh termed "direct 

 adaptation." There is really no such thine. The 

 supposed mysterious property of direct adaptation is 

 always due to surv'ival by selection of organisms which 

 varied in many directions. 



J Abstracts of four Croonian Lectures de'ivered at the Royal Cotlege of 

 Physicians on June 14, 19, 21, and 26, by Prof. J. G. jVdami, F. R.S., Tem- 

 porary Lieiit.-Colonel C A.M.C. 



_ - Sir F.. Ray Lankester has in the British Medical J ouyntU taken excep- 

 tion 10 the use of this word; the author agrees that "vigorously" better 

 expr sses his meaning. 



NO. 2494, VOL. 99] 



Now if, there be one fact that is constantly being 

 impressed upon the student of immunity and the 

 workers in pathogenic bacteriology, it is that direct 

 adaptation, i.e., specific modification in response to 

 specific alteration in environment (within limits which 

 he would lay -down) is one of the basal phenomena of 

 living matter. It seems useful, therefore, to marshal 

 in order the data bearing upon these matters as they 

 present themselves to those engaged in medical re- 

 search. 



Problems of this nature are a priori most likely to 

 be solved by experiments upon the ver>' simplest, and 

 again up>on the most complex forms of life. For 

 problems of adaptation and heredity the bacteria 

 possess the supreme advantages of rapid reproduction 

 coupled (according to our present knowledge, or want 

 of knowledge) with a complete absence of the disturb- 

 ing influence of sex and conjugation. Certain bio- 

 logists are unwilling to regard the products of asexual 

 binary division as true generations. One very dis- 

 tinguished biologist had said that a long cultivation 

 of a bacterial growth is "one continuous individual." 

 This is an impossible position. The very idea of 

 individual connotes independent, or potentially inde- 

 pendent, existence. We might with equal logic, 

 basing ourselves on the continuity of the germplasm, 

 declare that all living beings constitute one continuous 

 individual. 



Adaptation in the Bacteria and the Evolution of the 

 Infectious Diseases. 



It is absurd to expand the Batesonian hypothesis 

 and imagine that whenever man became man he 

 acquired the germs of all bodily ills, and that the 

 purely human ailments were already there. Some 

 diseases, like tuberculosis, have been with us from 

 the remotest historical times, and even from pre- 

 historical, as witness the late Sir Armaud Ruffer's 

 studies in palaeopathology upon mummies of early 

 dvnasties, and the recognition of caries and pyorrhoea 

 in permian fishes and tertiary- three-toed horses. This 

 is only to be exf>ected. The bacteria are among the 

 earliest of all forms of life. Drew, from his studies 

 of the calcareous ooze of the Florida lagoons, showed 

 that a dentrifying bacillus caused the deposition of 

 chalk out of sea-water. Walcott has discovered 

 Cvanophyceae and possible micrococci in the oldest 

 of all sedimentarj- rocks, the Algonkian. 



But this does not mean that all orders of patho- 

 genic bacteria and microbes have always been with 

 us. Zymotic phenomena must run parallel with geo- 

 logical. The vast majority of fossils are remains of 

 species and genera which have passed away, but 

 certain species, and, indeed, certain genera, have 

 existed unchanged through countless ages to the 

 present day. The brachiopod Lingula of the Cam- 

 brian rocks is to be found to-day living buried in the 

 sand b'etween the tide-marks in the Tropics. The 

 pearly Nautilus, Limulus, Ceratodus, and Anaspides 

 have remained apparently unaltered for extraordinarily 

 long periods of geological time. 



The same would seem to be true with respect to 

 zymotic diseases and their causative agents. Many 

 of the plagues and epidemics mentioned by early 

 writers are unrecognisable to-day. The tritest ex- 

 ample of a disease which has come and gone is the 

 malignant "sweating sickness," which, first noted in 

 1485, was last heard of in 155 1. As regards diseases 

 still with us, whatever view be taken regarding the 

 origin of syphilis, it is certain that this was unknown 

 in Eg3pt and in Rome at the time of Galen. 

 Diphtheria and cholera, both with absolutely charac- 

 teristic symptoms, were unknown in Europe until the 

 beginning of the nineteenth centun,'. Even if these 



