Nos. 618-619] NOTES AND LITERATURE 



367 



for example, the work of T. H. White on making new varieties 

 of tomatoes by adding large quantities of fertilizers, which is 

 rather hesitatingly cited. But perhaps one should criticize mat- 

 ter which does not appear rather than matter which does appear. 

 In other words, if the reviewer may express his own hope in the 

 connection, it is to see a more extended/ well-rounded discussion 

 of the action of the factors of environment in a later addition. 



The statistical study of variation has been given a very pleas- 

 ing treatment. The mathematician will undoubtedly complain 

 that it is amateurish because it is given with a minimum of 

 technical language. But just there lies its value in such a 

 text-book. The necessary statistical tools are described so 

 clearly that the elementary student can hardly err in their use. 

 The more advanced student is properly directed elsewhere. 



The physical basis of heredity is also discussed with great 

 independence. The chromosome hypothesis is accepted without 

 reservation. Cytological details not bearing directly on the sub- 

 ject in hand are not even mentioned, while those described — 

 though accurate as far as they go — are somewhat diairraminath'. 

 It will be interesting to see how this treatment works out in the 

 classroom. No doubt many will find it a welcome change from 

 the interminable details of unknown significance that often fill 

 the pages of books on genetics. At the same time it is perhaps 

 to be regretted that the difference between the higher plants and 

 the higher animals in gametogenesis, and the bearing on genetics 

 of the conflict between supporters of parasynapsis and tele- 

 synapsis, are not given more space. 



A hundred and fifty pages are devoted to Mend* ! 

 pretations of breeding facts. A wealth of illustration is used, 

 and almost all types of Mendelian ratios are represented, 

 although it is not easy to gather them together in a general 

 ensemble. The older treatments of Plate and of Goldschmidt, 

 where every theoretical modification of the Mendelian ratio was 

 mentioned and then a case in point cited, had their value from 

 a pedagogical standpoint, and it is rather to be deplored that 

 their use was not continued. The newer data, in particular the 

 work of Morgan and his students, is admirably presented, how- 

 ever. For the first time text-book treatment of crossing over, 

 interference, and the various other phenomena discovered in 

 Drosophila, is given in such a manner that the beginning -tin hut 

 should be able to grasp the essential points without difficulty. 



Interesting chapters on species hybridization,- pure lines and 



