no 



SCIENCE 



[N. S. Vol. XXIX. No. 733 



to the square of their accuracy that Darwinism 

 has been played oi^t since the appearance of 

 de Vries's ' Mutations-theorie.' " It can not 

 be said that Professor Poulton doth protest 

 too much, but he certainly errs in the same 

 direction as those against whom his protest is 

 directed, in that he endeavors, unnecessarily 

 for his purpose, to minimize the importance 

 of both mutations and Mendelism, instead of 

 recognizing them as factors in bringing about 

 conditions upon which natural selection may 

 act. 



The first essay is a discussion of the age of 

 the earth, considered from the standpoint of 

 an evolutionist, and had for its exciting cause 

 Lord Salisbury's presidential address to the 

 British Association at the Oxford meeting in 

 1894. The question is an old one and has had 

 many answers, none of which are very definite, 

 nor does Professor Poulton's discussion of it 

 lead to any more definite conclusion than that 

 the earth must be old enough to have allowed 

 time for the accomplishment of evolution. 

 This will, no doubt, be quite acceptable to 

 evolutionists. Similarly, the second essay, on 

 " What is a Species ? " while interesting as a 

 discussion of the meaning that has been ap- 

 plied to the word species at different times, 

 naturally leaves one with a sensation of in- 

 definiteness, and the three succeeding essays, 

 on " Theories of Evolution," " Theories of 

 Heredity " and " The Bearing of the Study 

 of Insects upon the Question ' Are Acquired 

 Characters Hereditary ? ' " discussions of the 

 respective merits of the old antagonists, 

 Lamarckism and Weismannism, while more 

 interesting reading than the majority of such 

 discussions, yet, again, are quite as futile as 

 these so far as any settlement of the questionis 

 at issue are concerned. 



The sixth and seventh essays are largely 

 historical. The sixth deals with the views 

 concerning inheritance advanced by the an- 

 thropologist, Prichard, in his "Eesearches 

 into the Physical History of Mankind" (2d 

 edition, 1826). These constitute a remarkable 

 anticipation of the conclusions later advanced 

 by Weismann concerning the non-transmissa- 

 bility of acquired characters, as a quotation 



of one sentence from the work will suffice to 

 show. Prichard says " changes produced by 

 external causes in the appearance or constitu- 

 tion of the individual are temporary, and, in 

 general, acquired characters are transient; 

 they terminate with the individual, and have 

 no influence on the progeny." 



In the seventh essay Huxley's position on 

 the question of natural selection is considered, 

 and it is maintained that he " was at no time 

 a convinced believer in the theory." This 

 conclusion can not but seem strange when one 

 recalls that Huxley received from Darwin the 

 title of " general agent " by the vigor with 

 which he wrote and spoke on behalf of the new 

 theory. Professor Poulton certainly makes 

 out a strong case, claiming that Huxley, while 

 a strong evolutionist, was unable to appreciate 

 the bearings of the theory of natural selection, 

 his inclinations being towards the study of the 

 " engineering side of nature," rather than 

 towards the contemplation of structure in re- 

 lation to environment. But in opposition to 

 Professor Poulton^s conclusion one may oppose 

 Huxley's own statements. Writing to Darwin 

 in 1859 he says: 



As to the first four chapters [of the Origin], 

 I agree thoroughly and fully with all the prin- 

 ciples laid down in them. I think you have dem- 

 onstrated a true cause for the production of spe- 

 cies, and have thrown the onus probandi, that 

 species did not arise in the way you suppose, on 

 your adversaries. 



True, he goes on to confess that he did not 

 feel that he had fully realized the bearings of 

 the theory of natural selection, and criticizes 

 the adoption of the principle that natura non 

 facit saltum and the slight importance as- 

 signed to continued physical conditions as a 

 cause of variations. These criticisms do not, 

 however, apply to the theory of natural selec- 

 tion; they concern only the question of the 

 origin of variations. Further, writing in 

 1880, he said: 



I hope you do not imagine because I had noth- 

 ing to say about " natural selection [in " The 

 Coming of Age of the Origin of Species "], that 

 I am at all weak of faith on that article. On the 

 contrary, 1 live in hope that as paleontologists 

 work more and more ... we shall arrive at a 



