424 



SCIENCE 



[N. S. Vol. XXXI. No. 794 



■wind. This represents a type of the Ascomy- 

 cetes adapted to wind dissemination of the 

 spores. Another type is represented by Asco- 

 holus immersus with broad elliptical asci, and 

 large spores which are held together by a 

 broad gelatinous investment so that they re- 

 main in a group as a single projectile as they 

 are shot from the ascus to a distance of 20-35 

 cm. This mass, which is 2,000 times the vol- 

 ume of a basidiospore, is too heavy for wind 

 dispersal. It falls on the surrounding herbage 

 where the spores may be devoured by herbi- 

 vorous animals and gain dispersal after pass- 

 ing through their digestive tract. 



The rate of fall of the spores of the Hymen- 

 omycetes was used to test the theory known as 

 Stokes's law relating to the fall of microscopic 

 spheres in air, and it was confirmed to within 

 46 per cent. For determining the velocity of 

 spore fall under direct observation through the 

 microscope the author employed an ingenious 

 device of an automatic electric recorder, 

 the position of a spore, as it successively 

 passed by spaced horizontal threads in a 

 Eamsden ocular, being registered by a tap- 

 ping key controlled with the left hand. 



The illustrations and press work of this 

 book are good, and besides the very interesting 

 and important discoveries, it is full of stimu- 

 lating suggestions and possibilities for further 

 investigation. 



Geo. F. Atkinson 



Charles Darwin and the Origin of Species. 

 Addresses, etc., in America and England in 

 the year of the two anniversaries. By Ed- 

 ward Bagnall Poulton. New York, Long- 

 mans Green and Co. 



It is fitting that upon November 14, 1909, the 

 anniversary of the publication of the " Origin 

 of Species," there should be published this 

 memorial volume; fitting also that it should 

 be written by a friend and advocate of Dar- 

 win's views in their entirety. Besides the ad- 

 dresses the volume contains some unpublished 

 letters of Darwin and also a preface in which 

 the author takes occasion to express his atti- 

 tude toward the modern contributions to the 

 study of evolution. 



Nothing is more evident than that the 

 younger generation of scientists has departed 

 somewhat from the Darwinism of a generation 

 ago. That fifty years' study of Darwin's great 

 theories, by both friends and enemies, has es- 

 tablished the general theories of which he was 

 the most notable advocate upon an unshakable 

 basis is very clear. But equally clear is it that 

 this same half century has raised difficulties 

 as to Darwin's special explanation of the 

 method of evolution; difficulties so great that 

 most of the younger generation of scientists 

 are unable to accept Darwinism in its entirety 

 as an all-sufficient theory. These difficulties 

 have arisen not simply in the minds of Dar- 

 win's enemies, but in those of his friends also. 

 That some solution of these difiiculties is to 

 be found is the belief of every admirer of Dar- 

 win, and moreover every admirer of Darwin 

 must feel that this great master so fully ex- 

 hausted the study of his great law of natural 

 selection that little can be hoped for further 

 study along the same lines. It is difficult to 

 resist the belief that the removal of the diffi- 

 culties that have arisen must come along new 

 lines of study and not by the further ex- 

 ploitation of the old ones. 



Poulton, however, apparently thinks other- 

 wise and conveys the impression of holding 

 that of the modern theories, that which is new 

 is not true and that which is true is not 

 new. The only real contribution to the discus- 

 sion since Darwin that Poulton admits is 

 AVeismannism, and this he admits, seemingly, 

 simply because it places the great theory of 

 Darwin in a position " far higher than that 

 ever assigned to it by Darwin himself." Of 

 the mutation theory, which most thinkers to- 

 day recognize as at all events decidedly stimu- 

 lating, Poulton can only speak with a sneer, 

 both at the theory and at its chief exponent. 

 Some of Darwin's friends have been pleased to 

 feel that Darwin really recognized mutations 

 under the phrase " evolution per saltum " as 

 a part of his theory. But Poulton is at pains 

 to repudiate this idea entirely and to insist 

 that Darwinism is a theory of evolution by 

 minute steps and one of which any conception 

 of mutation forms no part. 



