Physiologie. 167 



6) An increase in the general illumination of an organism may 

 cause an increase in activity, vvhile a sudden decrease of intensity 

 causes a still greater increase in activity in the same organism at 

 the same time. 



7) An increase in light energy may produce the same effect on 

 reactions as a decrease in heat energ3 r . 



8) Acids, certain narcotics and salts, and at least one alkali, 

 may cause a change in the sense of reaction from negative to posi- 

 tive im Gammanis pidex. Any condition which acts as a depressant 

 may cause Ranatya or Arenicola larvae to become negative. 



9) The stimulating effect of the different rays in the spectrum 

 is specific. But it is not the same in all organisms. 



10) Reactions to light are variable, modifiable and in general 

 adaptive. Moore. 



Osterhout, W. J. V., The permeability ofliving cells to 

 salts in pure and balanced Solutions. (Science. II. 34. p. 

 187—189. Aug. 1911.) 



1. The usual method of determining osmotic pressure by plas- 

 molyzing in salts of Na and K is very erroneous. Salts of Ca gave 

 more nearly the true osmotic pressure. 



2. Since one substance may greatly affect the penetration of 

 another it is unsafe to use the common method of adding a toxic 

 to a non- toxic substance and judging the penetration of the former 

 by, the plasmolytic action of the mixture. 



3. It is possible to State which salts penetrate and at what rate 

 of speed, and also how various salts affect the permeability of the 

 plasma membrane. 



4. From these data we have a definite clue to the nature of 

 the plasma membrane. Since all the salts studied penetrate it seems 

 certain that the membrane cannot be lipoid because these salts are 

 not soluble in lipoid. Its behavior towards balanced Solutions (toge- 

 ther with other facts) indicates unmistakably that the membrane is 

 proteid in nature. 



5. Antagonistic salts such as NaCl and CaCl, hinder or prevent 

 each other from entering. To such an extent is this true that by 

 choosing Solutions of NaCl and of CaCl which are not quite strong 

 enough to plasmolyze we produce by mixing them together a Solu- 

 tion which plasmol3 r zes strongly. 



The fact that these salts hinder or prevent each other from 

 entering may explain why they act as antidotes to each other. But 

 since they may eventually penetrate to some extent we must attach 

 importance to their effect on the protoplasm within the cell as well 

 as to their effect on the plasma membrane. These two effects may 

 be very similar. Moore. 



Preston, J. F. and F. J. Phillips. Seasonal Variation in the 

 food reserves oftrees. (Forestry Quart. IX. p. 232—243. Jul. 

 1911.) 



An examination of 9 representative forest trees, at intervals 

 from one to two weeks from October to June resulted in the fol- 

 lowing conclusions: 



1. There is in the stems of all trees in temperate climat^s a 

 reduction in November and December of the amount of starch 

 present in autumn, the reduction being so great in some trees as 



