430 



SCIENCE. 



[N. S. 70L. IV. No. 91. 



The forces determining the positions of leaves: 



By E. I^. Day. 



Specimens of Phaseolus, Taraxacum, Cu- 

 curbita, Mcotiana, Helianthus and Ariste- 

 ma were grown under the following condi- 

 tions: 



In darkness and in light. 



a. Upright position. 



b. Horizontal. 



c. Inverted. 



d. Horizontal or planostat. 



"Without discussion of the experimental 

 details, it may be said that the conclusion 

 of Vines that photo-epinasty does not ex- 

 ist is confirmed, and it is also concluded 

 that epinasty and hyponasty are inherent 

 properties whose reactions may be sup- 

 pressed but whose general nature is not 

 influenced by external conditions. Sec- 

 ondly, the results obtained bear directly 

 on the recent conclusions of Vines and the 

 current and accepted generalizations. 



Vines' statement that dorsiventral organs 

 are never apogeotropic is by no means sub- 

 stantiated, nor is it by any manner of rea- 

 soning to be inferred from the develop- 

 mental history of the leaf. It might well 

 be applied, however, to stems or flower 

 structures. It may be seen from the 

 author's and other results that dorsiventral 

 leaves may be diaheliotropic, diageotropic 

 or apogeotropic, epinastic or hyponastic. 

 The factor determining the position of the 

 leaf in every instance is the heliotropic ten- 

 dency, which so far overbalances the influ- 

 ence of the other two forces that their re- 

 actions are suppressed. The position of the 

 leaf then is a physiological, not a mechani- 

 cal resultant, and may not be expressed by 

 the parallelogram of forces as designed by 

 Krabbe in 1889. 



The bacterial flora of cheddar cheese : By H. 



L. KussELL and John Weinzirl. 



The study made by the author deter- 

 mines quantitatively and qualitatively the 



bacterial flora of our American cheddar 

 cheese at the various phases of the ripening 

 process. The first change from that in the 

 milk is a diminution in number for the 

 first ten days. In this the different species 

 all suffer loss. Soon there begins an enor- 

 mous development of organisms that is con- 

 fined to lactic acid group of bacteria. The 

 digesting and gas-producing bacteria grad- 

 ually decrease in numbers. Succeeding this 

 stage of bacterial increase is a period of 

 gradual decline, which continues through- 

 out the life of the cheese, until it is almost 

 sterile in the course of a year or two. The 

 physical changes that mark the curing of 

 the cheese begin to appear synchronously 

 with the marked development of lactic acid 

 bacteria. The authors hold that these 

 facts cannot be reconciled with the theory 

 that the digesting bacteria are the active 

 agents in the curing. 



The pollen and stigma ofAriscema : By "W. W. 



EOWLEE. 



The author described the androecium and 

 gynoecium of Ariscema triphyllum and A . Dra- 

 contiam. He noted the peculiarities of the 

 consolidation of the stamens, the open style 

 with the stigmatic hairs not only on the 

 surface of the stigma, but also on the inner 

 surface of the tube and forming a stigma 

 like tuft on the inner surface of the ovary. 

 The pollen in one case was found to have 

 already germinated within the anthers, and 

 the tubes had folded back and forth upon 

 themselves. Other cases examined did not 

 show the same growth. 



Studies in nuclear phenomena, and the develop- 

 ment of the ascospores in certain Pyrenomy- 

 cetes : By Mary A. Nichols. 

 The results of the author's study point to 

 the conclusion that a sexual process may 

 be present in some members of the Sphceriacece^ 

 and absent or very degenerate in others. 

 In Ceratostoma hrevirostre the origin of the as- 

 cospore is distinctly traceable to a fusion of 



