January 16, 1903.] 



SCIENCE. 



Ill 



suming this star to be near the center of 

 the universe, it would follow that 



<r = 3.9 X 10-"c? 



in which d is the density of ordinary air. 

 That is, the density of the universal gase- 

 ous medium in the solar system would be 

 of the same order of magnitude as the 

 ether. On this basis the density of the 

 mediiun at a distance of 585,000 miles 

 from the center becomes equal to that of 

 ordinary air, and the concentric sphere of 

 the medium within this radius would have 

 a mass about seven times that of Jupiter, 

 a mass entirely too small to be conspicuous 

 in celestial space. 



Condition of Atmosphere, Horizon, and 

 Seeing at the Lowe Observatory, Echo 

 Mountain, California: Professor Edgar 

 L. Lakkin, Director Lowe Observatory. 

 Read by title. 



The officers elected for the next meeting 

 are: 



'Vice-President — Otto H. Tittmann, Superin- 

 tendent United States Coast and Geodetic Survey. 

 Secretary — Professor Laenas G. Weld, Univer- 

 sity of Iowa. 



Charles S. Howe, 



Secretary. 



SCIENTIFIC BOOKS. 

 Ueier den derzeitigen Stand der Descendenz- 



lehre in der Zoologie. Von Dr. H. E. 



ZiEGLER^ Professor an der Universitat Jena. 



Gustav Fischer. 1902. Pp. 54, with 4 



text-figures. M. 1.50. 



On the occasion of the seventy-third meet- 

 ing of the German ISTaturalists and Physi- 

 cians in Hamburg, September, 1902, the gen- 

 eral question of the present status of the doc- 

 trine of organic evolution was presented in 

 three lectures — by a botanist (de Vries), a 

 paleontologist (Koken) and the zoologist, 

 Ziegler. The last lecture is now somewhat 

 extended by notes and appendices and pub- 

 lished under the title given above. 



It is an interesting account of the present 

 standing of the great Descendenzlehre in 

 zoology, given in a temperate spirit; a good 

 lecture for the occasion and the place in 

 which it was delivered. 



The subject is considered under four sec- 

 tions : (1) The general theory of organic evo- 

 lution, (2) natural selection, (3) inheritance 

 theories and (4) the application of evolution 

 to the origin of mankind. 



Of these, the first section is treated with a 

 firmer hand, as is justified by the state of our 

 knowledge, and the author reviews interest- 

 ingly, from the zoological side, some of the 

 evidences in support of evolution. He points 

 out that the general proposition has been so 

 strengthened by the researches of the past 

 forty years that all naturalists agree in ac- 

 cepting it as established. We have no other 

 rational theory of the origin of plants and 

 animals, and, notwithstanding the controver- 

 sies as to the factors that have brought about 

 the diversity of organic life, the fact of evolu- 

 tion as a process of creation is no longer 

 seriously challenged. 



But the compelling arguments in support 

 of evolution do not hold in equal force for 

 natural selection or any other particular 

 theory. Here we have conflicting opinions, 

 but they do not seriously affect the main 

 contention. As Huxley, one of the greatest 

 supporters of natural selection, said : ' If the 

 Darwinian hypothesis were swept away, evolu- 

 tion woidd still stand where it was,' and the 

 same thing can be said in reference to any 

 theory of evolution that has been offered since. 



In regard to natural selection, Ziegler comes 

 to the position of so many working zoologists, 

 that as a factor it is not adequate by itself 

 to afford an explanation of variation and de- 

 velopment. In many instances its action is 

 clear — as when variations which are of direct 

 use to the animal are fostered by natural 

 selection, but many other cases like the great 

 development of the backward-directed tusks 

 of the mammoth, and horns of other animals, 

 can not be explained by natural selection. 



The third section is more lightly treated. 

 The inheritance theories of de Vries, Nageli, 

 Haaeke and Weismann receive passing men- 



