26 



HARDWICKKS SCIENCE-GOSSIP. 



individuals take place through the action of the 

 environment, he will not admit that these changes 

 are inherited ! Yet he believes in changes in breeds 

 of domestic animals through "selection." How can 

 selection act, if there is no inherent force to initiate 

 the change? If individual peculiarities are inherited, 

 then it is quite natural that a pointer puppy should 

 point ; but if they are not, why should he not 

 accidentally vary in some other direction ? There 

 must be some internal force rendering variation 

 possible, or the breeder might select for ever without 

 producing any effect. Practically, in every-day life 

 every one acts upon the assumption that individual 

 peculiarities are transmitted, with or without selec- 

 tion. Defects of body and mind, and liability to 

 succumb to certain diseases, are also only too well 

 known to be transmissible from one generation to 

 another. Deaf-mutes have children who are deaf- 

 mutes, though atavism hinders all the children from 

 inheriting this defect ; and the same remark applies 

 to persons with supernumerary toes and fingers. 

 Where one parent has been the victim of phthisis or 

 of insanity, the children are in danger of succumbing 

 to the same disease ; where both parents have fallen 

 victims, the chances are increased to a frightful 

 degree. It is almost impossible to imagine how the 

 strongest prepossessions against heredity can hold 

 out in the face, not only of countless arguments from 

 science, but x)f the practical experience of mankind 

 in all ages. 



Mr. Wallace devotes one chapter only to the 

 geological evidence of evolution ; but even in the 

 very brief sketch he gives, there appears such over- 

 whelming evidence of the influence of heredity and its 

 effects in perfecting or aborting every organ of 

 animals, and the slight, fine modifications in certain 

 directions by which the changes from fossil to 

 existing species have been effected, that one thinks he 

 cannot remain unconvinced, and that he must beheve 

 these modifications to be hereditary. We almost 

 doubt the evidence of our eyes when we read this 

 passage, " There is now much reason to believe that 

 the supposed inheritance of acquired modifications — 

 that is of the effects of use and disuse, or of the 

 direct action of the environment — is not a fact." 

 That is, we are to believe that all the modifications 

 leading steadily upwards or downwards, the limbs 

 perfected for speed of the horse and deer, the utter 

 absence of limbs in certain lizards, the specialisation 

 of the dentition of animals varying cusp by cusp and 

 tooth by tooth, the improvement in brain capacity 

 from Eocene times to our own, the persistence of 

 rudimentary organs not only useless but dangerous to 

 their present possessors ; we are gravely asked to 

 believe that all these modifications are the result 

 of a series of accidents occurring generation after 

 generation with results more and more marked, yet 

 all uninherited and accidental ! Can any one who 

 has been impressed with the grand simplicity and 



uniformity of the great Laws of Nature, believe that 

 evolution is due to an infinite number of happy 

 accidents? We know of a law which answers al! 

 those requirements of simplicity and uniformity of a 

 great Law of Nature, which is in harmony with all 

 the apparently complicated phenomena of life, which 

 solves problems otherwise insoluble, the Law of the 

 Action of the Environment upon Irritable Proto- 

 plasm. And we are asked to set it aside as non- 

 existent, and believe in innumerable accidental 

 variations, as an efficient substitute ! 



Mr. Wallace refers, with high approval, to Professor 

 Weismann's now celebrated lectures. If the theory 

 which Professor Weismann considers he has proved in 

 his laboratory is contradicted by the evidence of 

 zoologists and paleontologists, as well as by the 

 universal practical experience of mankind, then it is 

 clear that laboratory work will not explain every- 

 thing, and that the methods employed have been 

 erroneous. But what shall we say when we are 

 asked to accept a theory of which there is not one 

 iota of tangible proof, which is, if anything, entirely^ 

 contradicted by facts, and to accept this hypothesis 

 as the only side of the medal ? Professor Weismann's 

 theory in brief is that the "substance which forms 

 the foundation of all the phenomena of heredity, in my 

 opinion, can only be the substance of the germ-cells, 

 and this substance transfers its hereditary tendencies 

 from generation to generation, and is always unin- 

 fluenced in any corresponding manner by that which 

 happens in the lifetime of the individual. If 

 these views be correct, all our ideas upon the trans- 

 formation of species require thorough modification, 

 for the whole principle of evolution by means of 

 exercise (use and disuse) as proposed by Lamarck, 

 and accepted in some eases by Darwin, entirely 

 collapses."* 



When we read that views held not only by 

 Lamarck, but by a host of illustrious men of science 

 who have evidence at their command, which 

 Lamarck and Darwin would have given worlds to 

 possess, are to collapse before a certain theory, we 

 expect this theory to have been founded on some- 

 thing that has at least been seen and observed. But it 

 turns out that everything has to be "assumed." The 

 assumption is that only a part of the germ-cell is 

 used in the formation of the future animal ; the 

 remainder of the cell as " germ-plasm " is reserved to 

 be handed on to future generations. I have 

 endeavoured to reproduce this idea by a rough 

 diagram. 



" The germ cells f are not derived at all, so far as 

 their essential substance is concerned, from the body 

 of the individual, but they are derived directly from 

 the parent germ-cell. " The body (somatic) cells have. 

 Prof. Weismann repeatedly declares, nothing what- 

 ever to do with the production of the germ -plasm. 



* " Biological Memoirs," p. 69. 



t Ibid. p. 168. 



