266 Descendenz und Hybriden. — Morphologie und Teratologie. 



a short consideration of de Vries' mutation theory is given. 

 Chapter three, on correlated variations, has to do only with 

 animal forms. In the part dealing with the causes of variations, 

 the next two chapters are concerned with those of a blasto- 

 genic nature, in which Mendel's principle is discussed and 

 reference made to non-sexual reproduction and to bud Variation. 

 In chapter six, entitled, „certain laws of Variation", animal forms 

 are again almost entirely considered, though the results of 

 de Vries, which support the author in the conclusion that 

 the effect of environmental conditions diminishes rapidly from 

 the time of impregnation onwards, are spoken of. In the three 

 following chapters the effect of change in certain environmental 

 factors is taken up, including temperature, light and moisture, 

 as well as the question of food supply and of the effect of 

 certain bye-products of metabolism. In connection with these 

 topics, questions pertaining to plant physiology recieve notice. 

 The final section on Variation in its relation to evolution 

 includes two chapters, one on the action of natural selection on 

 variations, and another on adaptive variations. Referring to 

 cumulative effects of conditions of life on both plants and 

 animals, in altering the characteristics of the organisms, the 

 author points out that these instances are not to be regarded 

 as examples of the inheritance of acquired characteristics, but 

 to the fact that the germ plasm has reacted simultaneously 

 with the body tissues, to environmental changes. 



H. M. Richards (New York). 



COUTAGNE, [G.j, De la polychrom ie polytaxique fl orale 

 des vegetaux spontanes. (C. R. de l'Acad. desSc.de 

 Paris. T. CXXXIX. No. 1. 4 juillet 1904. p. 77—79.) 



Chez les vegetaux dont les fleurs presentent plusieurs 

 taxies de couleurs differentes, certaines d'entre elles semblent 

 toujours incapables de soutenir la kitte pour l'existence (gene- 

 ralement les formes ä fleurs blanches). Chaque fois qu'elles 

 apparaissent spontanement (sous l'influence de causes encore 

 inconnues d'ailleurs) la selection naturelle les elimine ou tout 

 au moins s'oppose ä Ieur multiplication. Mais le fait n'est pas 

 constant et chez certaines especes il arrive que les diverses 

 taxies (meme la taxie ä fleurs blanches) presentent une egale 

 rusticite. Un meme caractere, l'absence de pigment, par exemple, 

 peut donc etre lie correlativement, tantöt chez teile espece ä 

 une particularite physiologique defavorable, tantöt chez une autre 

 espece ä une particularite physiologique favorable. 



L'attention des botanistes n'a ete appelee que tout recem- 

 ment sur les phenomenes mendeliens, en sorte que bien des 

 taxies ont ete vraisemblablement decrites comme especes diffe- 

 rentes, surtout lorsque leur distribution geographique £tait diffe- 

 rente de celle du type atiquel on les comparait. a. Giard. 



