Varietäten etc. — Physiologie. 215 



metes of both types, but certain mutative changes are sex limited. 

 In bis discussion the writer designates the two types of gametes as 

 « and ß gametes. The former are those which bear the most distinc- 

 tive specific characters of the various forms, whereas the latter bear 

 the more general character. The known facts seem to be accounted 

 for if we assume that in fertilization the conjugation of an « with 

 a ß gamete ordinarily takes place, but not the conjugation of two 

 /9-gametes. In certain cases it seems that fertiüzation takes place by 

 the fusion of two « gametes and it appears likely, also, that some 

 species produce no ß gametes. Some species produce « and ß ga- 

 metes of both sexes. Others do not seem to do so. It sometimes 

 seems to be the case that the female gametes are all «. When a 

 muiation takes place the modified character is perhaps Mendelian 

 if it is borne by both « and ß gametes, but non-Mendelian if it 

 affects only the « gametes of a species in which fertilization takes 

 place by the fusion of an « with a ß gametes. The writer would 

 by no means give the Impression that there are not many pheno- 

 mena which remain obscure, but he wishes to emphasize very 

 strongly that a flood of light is thrown upon the Oenothera-situation 

 by the conception of non-equivalent gametes. 



It seems to the writer that the Oenothera-situation is Clearing 

 up. One should not draw conclusions of too sweeping a nature. It 

 may confidently be stated, says the writer, that the appearance of 

 mutations in Oenothera is not due to Mendelian segregation, and 

 that the Mendelian method of attack has been utterly fruitless. It 

 is freely admitted that the mutation processes themselves are hardly 

 understood at all, and that further work must decide whether or 

 not mutation is always or ever conditioned by previous hybridization. 



M. J. Sirks (Bunnik). 



Blanc, L., Recherches experiraentales sur l'influence 

 des variations de temperature sur la respiration des 

 plantes. (Revue gener. de Botanique. XXVIII. p. 65—79. 1916.) 



Cette etude a ete divisee en trois parties: 



Une premiere serie d'experiences avait pour but de chercher 

 quel est, dans les deux cas, le degagement de CO2 presente par 

 une plante exposee d'abord ä une temperature T°, puis brusquement 

 ä une temperature E° plus petite que la premiere. 



Dans une deuxieme serie, l'auteur ramene la plante ä la tem- 

 perature initiale apres l'avoir fait passer par une temperature inter- 

 mddiaire plus elevee ou plus basse que la prec^dente. II mesure 

 remission de gaz carbonique soit dans les diverses phases, soit 

 dans les deux phases extremes seulement. 



Enfin il etudie, dans une troisieme partie, comment se fait le 

 passage du regime respiratoire d'une temperature T au regime 

 respiratoire ä une temperature T' differente de la premiere. 



Dans les exp^riences auxquelles l'auteur s'est livre il ne s'est 

 occupe que du degagement de gaz carbonique. Ce dernier etant ä 

 la fois le resultat des oxydations compietes ou incompietes qui se 

 produisent dans les tissus vdgetaux et le produit de certains dedou- 

 blements qui peuvent se manifester dans les cellules rend un compte 

 plus exact de l'intensite respiratoire que la mesure de l'absorption 

 d'oxygene. Dans cette mesure on neglige, en effet, l'influence de 

 la respiration intramoleculaire. 



Des experiences, decrites par l'auteur, on peut tirer les con- 

 clusions suivantes: 



