Varietäten etc. — Physiologie. 243 



longueur beaucoup plus grande. I, le facteur d'empgchement, en 

 etat homozygote, agit par supprimer la production des aretes late- 

 rales, mais il n'est pas suffisamment puissant pour pouvoir empgcher 

 absolument le ddveloppement des aretes moyennes, d'oü Ton pourra 

 comprendre la raison pourquoi meme dans le parent mutique 

 Nogenasi quelques ar€tes moyennes courtes peuvent se produire. 

 Quand le facteur d'empechement est en etat heterozygote, on voit 

 que la conduite des aretes laterales est tres variable meme dans un 

 £pi. La grande diversite de longueur des aretes est principalement 

 due ä la combinaison diverse des deux facteurs A et E. 



Jongmans. 



Brown, W. H. and G. W. Heise. The application ofphoto- 

 chemical temperature coefficients to the velocity of 

 Carbon dioxide assimilation. (Philippine Journ. Sc. C. Bot. 

 XII. p. 1-24. 3 Fig. 1917.) 



The authors have undertaken a series of experiments for the 

 further investigation of the question of the temperature coefficients 

 of photosynthesis. They give in the present paper a discussion of 

 the literature on the subject and analyze the work of Van Amstel, 

 on Elodea, of K reusler, on Rubus fruticosus, of Prjanischnikow, 

 on Typha, of Lubimenkow, of Matthaei, on Cherry Laurel 

 {Prunus laurocerasus), of Blackman and Matthaei, on Helianthus. 

 After a general discussion of the results of this analysis they 

 publish the following conclusions: 



The result of the work on carbon dioxide assimilation, here 

 discussed, show temperature coefficients of from 1.00 and 1.40 over 

 long ranges of temperatures which are favorable for this process. 

 They are much smaller than those for most vital phenomena, which 

 at similar temperatures are generally held to be of the order of 

 magnitude required by the van 't Hoff principte. 



These coefficients are of the same order of magnitude as photo- 

 chemical coefficients, which is not surprising in view of the fact 

 that carbon dioxide assimilation is effected by light. Jongmans. 



Brown, W. H. and G. W. Heise. The relation between 

 light intensity and Carbon dioxide assimilation. 

 (Philippine Journ. Sc. C. Bot. XII. p. 85—97. 2 Fig. 1917.) 



The authors bring here a review of the literature on the sub- 

 ject. The published work on photosynthesis does not Warrant the 

 generally accepted conclusion that carbon dioxide assimilation in 

 plants is proportional to the light intensity. Instead they indicate a 

 progressively smaller augmentation of the rate of assimilation for 

 each increase in light intensity. This decrease in the rate of augmen- 

 tation continues until a point is reached at which further increase 

 in light produces no measurable increase in assimilation. 



Jongmans. 



Goodspeed, T. H„ Notes on the germination oftobacco 

 seed. III. (Univ. California Publ. in Bot. V. p. 451 — 455 Apr. 

 3, 1919) 



A reexamination of the relation of light and darkness to ger- 

 mination showing "no doubt that the seed of five representatire 



