July 5, 1900] 



NA TURE 



219 



also the basis on which Kassowitz founds his theory of 

 variation, which latter he regards as always due to the 

 action of the environment, translated in slight differences 

 1n the mode of breaking down and reconstruction jf 

 protoplasm. 



It is impossible to summarise vol. ii. in a review with 

 any hope of doing justice to the criticisms — some of them 

 undoubtedly clever— of contemporary writers on evolu- 

 tion, Weissmann especially coming in for lengthy and 

 severe treatment, particularly with regard to the theory 

 of determinants, and his peculiar views on the meaning 

 of amphimixis, natural selection, and acquired characters. 

 It must sufifice to say that Kassowitz offers — assuming 

 the validity of his fundamental hypothesis— what he 

 : egards as convincing arguments to prove the essential 

 truth of Darwin's conclusions as to the inheritance of 

 adaptations, of the effects of use and disuse — in short, 

 of the gradually accumulated effects of the environment 

 on the somatoplasm, until the latter is so altered as to 

 affect the germ-plasm, and so fix and hand on the changes. 



The author regards the theories of pangenesis and 

 their like, equally with such as Haeckel's suggestions as 

 to transmissions of modes of vibrations, as far too com- 

 plex : his chief objections are that it is to him incon- 

 ceivable how every structural part could be represented 

 by a physical unit or by a mode of motion transferred to 

 the germ-plasm, and that he cannot see how those who 

 conceive this can get over the difficulty that such vibra- 

 tions would annul each other as their paths cross, or 

 that the pangenes, biophores, determinants, &c., would 

 get lost on the road. Further, these latter units are, by 

 hypothesis, themselves living, and hence the real 

 difficulty is only shelved. 



Kassowitz, however, only demands of his germ-plasm 

 that it be made up of a certain, and probably not a very 

 large number of similarly built and very complex, but 

 not infinitely complex, molecules. He does not suppose 

 that every form-unit of the future organism is repre- 

 sented, but that certain characteristic atom-groupings 

 out of the chemical units of the somatoplasm are utilised 

 in the architecture of the molecule of the germ -plasm, 

 and that in ontogeny these atom-groupings make their 

 effect felt, either directly or indirectly, by the way of 

 correlations of various kinds. 



This is true epigenesis. In the developing organism 

 every part is formed anew, from a substance in which 

 none is especially represented. The forms and arrange- 

 ments which ensue are simply the results of the activities 

 of the atom-groupings already there, working on the 

 materials supplied. When these latter have been assimi- 

 lated— /.i-. built up into protoplasm molecules— they 

 e.xert their cumulative effects on more substance, and 

 also modify those already present by serving as new 

 environment — and so the process of evolution proceeds. 

 Every now and again a slight variant gets its play, and 

 the results may be far-reaching ; but, on the whole, the 

 dominant play of the constellations of molecules at work 

 leads to what we term uniformity — a relative term. 



While fully appreciating and endorsing Darwin's con- 

 clusions as to the importance of artificial selection, 

 Kassowitz appears to undervalue the power of natural 

 selection, curiously enough, because he, like so many 

 others, cannot imagine it to be effective in the early 

 NO. 160I, VOL. 62] 



stages of adaptive changes. He thinks acquired char- 

 acters must have reached a certain stage of perfection 

 before natural selection can come into play, and argues 

 that when such a stage is reached selection is unneces- 

 sary, because so many individuals have already got the 

 adaptation. Kassowitz appears to me to here betray the 

 position of a laboratory philosopher as opposed to a field- 

 naturalist. His own hypothesis points to the laborious 

 accumulation of the effects of repeated stimuli and 

 repeated readjustments : some have survived, others and 

 far more have perished— is this not natural selection? 

 There seems to be some confusion of thought expressed 

 in implications that natural selection is incompetent to 

 explam the origin of variations, which primarily it was 

 never intended to do. 



In one or two cases, indeed, the Viennese professor 

 appears to me to have completely misunderstood the 

 position — to an extent so remarkable that the question 

 obtrudes itself, whether the whole argument must not be 

 vitiated into which such misapprehension has crept. 

 To quote one instance only. He admits that the struggle 

 for existence between closely allied varieties, races, or 

 species has resulted in the death of some races, &c., but 

 objects that many plants and animals in the past 



" nicht auf diesem Wege ihren Untergang gefunden 

 haben, sondern durch ungiinstige aussere Bedingungen 

 und feindliche Einwirkungen, also durch Trockenheit, 

 Ueberschwemmung, Kalte, Nahrungsmangel oder iiber- 

 legene Feinde vernichtet wurden, dass sie also nicht 

 im Concurrenzkampfe, sondern in einem mit ungen- 

 iigenden Mitteln gefiihrten Abwehrkampfe unterlegen 

 sind" (vol. ii. p. 131). 



But what does all this imply if not selection due to the 

 environment, and the struggle for existence ? 



To find a paragraph like this followed by the question 

 — Is it conceivable that such struggle for existence can 

 have led to any adaptive arrangement whatever? almost 

 takes away one's breath, because it is so totally beside 

 the issues raised by Darwin. The only explanation 

 appears to be that Kassowitz must be combating some 

 foreign misinterpretation of the views of the great master. 

 In spite of these and otfaer faults — I take it, no botanist 

 will accept the explanation of geotropism (vol. i. p. 280) — 

 this remarkable book appears to me to be a valuable con- 

 tribution to the literature of evolution, well worth read- 

 ing if only for the numerous criticisms and suggestions 

 scattered throughout its fascinating pages. These, by 

 the bye, are not few— there are nearly 750 pp. of text, and 

 more than that number of notes. It may be that 

 the glamour of the style and the beauty of the theme 

 have led me to pass too lightly over the failings, and to 

 over-estimate the good ; but the good is there. 



We have heard much of late about useful knowledge. 

 From the point of view of those who regard all know- 

 ledge as "useless" which cannot be directly applied to 

 the material improvement of man, the books before me 

 are indeed of little worth ; but to those who draw distinct 

 lines between knowledge and learning— information and 

 education — no apology will be needed for the conviction 

 that a treatise of this kind is especially welcome at the 

 present time. It is not only instructive, but stimulating 

 to a degree, and of the highest educational value to the 

 biologist of to-day. H. Marshall Ward. 



