Study of Spirogyra nit id a. 253 



upon the action of diastase on starch paste in the differenl 

 light rays, place the two centres of activity, the assimilative 

 and the hydrolytic, some distance apart. The activity of 

 the latter decreases, from the yellow toward both the more 

 and the less refrangible end of the spectrum, and it is to be 

 noted, that where the diastatic activity approximates that in 

 white light the plant makes a good growth, if not a per- 

 fectly normal one. This condition is seen under the red 

 screen, which in its action on diastase is exactly equivalent 

 to white light. 



The green, standing to white light, as measured by 

 diastatic activity, in the relation 1:1.14 has its starch 

 hydrated rather more slowly than in white light, yet the 

 decrease is not sufficient to stop nor to materially injure 

 the growth of the plant. 



The strange appearance and unusual activity of the pro- 

 toplasm produced under this screen suggests that the cell 

 is in a condition exactly the reverse of that induced by 

 yellow light. There, soluble carbohydrate predominated 

 over nitrogenous compounds ; here, the speed of production 

 of soluble carbohydrate is slightly lessened. The nitrogen 

 assimilation is then, probably, in excess, and it may be 

 that the proteid formed contains a larger proportion of 

 nitrogen than that formed under the usual conditions. 



Mendeleeff, in his " Principles of Chemistry," has called 

 attention to the fact that nitrogen content and protoplasmic 

 activity seem to go hand in hand through all forms of life. 

 Animals, whose tissues are so largely nitrogenous, possess 

 this activity in the highest degree. The higher plants, 

 with their great quantity of stable carbohydrate, have it 

 only feebly. But, on the other hand, in lower plant forms, 

 as for example in the zoospores, where the rapidity of 

 movement is quite comparable with that of animal life, 

 the nitrogen content is high, and remains so until the 

 active period is passed. When the spore fixes down it 

 develops a cellulose wall, loses its high percentage of nitro- 

 gen, and becomes in all respects a true plant. 



