162 SCIENCE PROGRESS 



then dealt with one by one, giving area, yield, and production of finished material 

 such as olive oil, silk cocoons, or ginned cotton ; it is not yet possible to include 

 tea, cocoa, rubber, jute, or gutta-percha in this section, because the available data 

 have been found too imperfect to justify publication. It is to be hoped that the 

 industries in question will help to remedy this omission. 



International trade statistics are abstracted in regard to the principal crops, 

 and data for consumption, price, ocean freight, and rates of exchange follow ; this 

 section especially is more fully developed than in the 191 3-14 issue. The last 

 section deals with production and prices of fertilisers. 



The list of authorities cited is in itself most useful as a reference for the 

 economist ; taking the countries of the world one by one, and commenting 

 where necessary on the statistical value of the data provided, it covers a hundred 

 pages. 



L. B. 



ZOOLOGY 



Organic Evolution. A Textbook. By Prof. R. S. Tull, PhD. [Pp. xviii + 729, 

 with 253 figures and 30 plates.] (New York : The Macmillan Company, 

 1917. Price i6.y. net.) 



It is strange, as the author points out in his introduction, that, in spite of the large 

 number of books that have been written on evolution and allied subjects, very few 

 have come from palaeontologists, yet they deal with the material that provides 

 the most direct proof of the phenomenon. A book, therefore, coming from such a 

 well-known authority as Prof. Tull is doubly welcome, and it is one that will prove 

 of great interest and use to all students of biology. The reviewer, unfortunately, 

 has not merely to praise or condemn a book as a whole, but if the former, as is 

 undoubtedly the case with the present volume, also to indicate points that do not 

 seem in keeping with the general high level of the work. On p. 199 Volvox is 

 referred to as a form showing the beginning of the differentiation of the germ cells 

 from the soma, but even more might be made of it, for according to recent 

 authorities still further specialisation is to be found among the cells of the " soma." 

 The account of the "air bladder" (sic) given on p. 318 suggests that its action 

 depends entirely upon the contraction of the body muscles. This, however, is 

 misleading, for it does not take into account the extraordinary rete mirabile and 

 gas gland with which that structure is provided nor the fact that it does not 

 contain air but a mixture of oxygen and nitrogen secreted and re-absorbed as 

 required. No histologist could let pass the footnote on p. 539 that " All bone 

 consists first of cartilage." A further statement cannot pass without challenge, 

 and that is that the lower jaw and tooth found in association with the Piltdown 

 skull does not belong to it and " is not even human but is that of a fossil 

 chimpanzee." This is a view which, for some unaccountable reason, has found 

 favour in America. The probability of such a fortuitous association is infinitely 

 remote, and, moreover, the jaw, which fits the skull, as near as can be ascertained, 

 quite well — again implying a marvellous coincidence — is utterly unlike that of any 

 chimpanzee, as a brief examination of the actual specimen will show. If the jaw 

 does not belong to the skull, we have in the Piltdown relics a still more remarkable 

 find, for, in addition to a peculiar type of human cranium, we have a jaw of an 

 entirely new genus of anthropoids. 



Apart from these matters for criticism, which are, after all, only of small 

 moment in view of the wide ground covered by the book, we certainly have one of 

 the most useful general accounts of evolution that have been published for some 



