236 Pennington — A Chemico-Physialogical 



imperceptibly smaller, until at the end of the fifth week 

 they have entirely disappeared from many of the cells, and 

 in the others are very few, and so small that strong mag- 

 nification is necessary in order to distinguish them. After 

 the starch is completely used up the cell contents rapidly 

 disappear, leaving finally only the empty cellulose walls. 



Green. — Under the green screens the growth of the 

 threads and the general appearance of the cells is excellent. 

 So far as the carbohydrate of the plant is concerned we 

 have a condition closely approximating that of the normal. 

 The starch granules are somewhat larger than those formed 

 under white light and are very plentiful. Sugar can always 

 be detected and is in the usual quantity. Tannin, likewise, 

 can be observed in the cells, but never in large amount. 



Though these green rays have so slight an action upon 

 the carbohydrates of the cell, the protoplasm is strongly 

 modified by their action. The quantity very materially 

 increases, so much indeed that the protoplasmic pellicle is 

 doubled in size. This pellicle is a denser mass than is 

 usually seen and is filled with small, dark granules. 



The most striking phenomenon is the exaggerated 

 motility of this protoplasmic layer, soon after placing the 

 plant under the colored screen. In about three or four 

 days after the commencement of the experiment this 

 activity is noticed, and it prevails for five or six days. 

 While actively motile the protoplasm shows a strong ten- 

 dency to collect at the ends of the cell, either pressing 

 closely against the cell wall, or lying some distance back 

 from it. Frequently protoplasmic currents are seen flowing 

 across the cell. These may run quite straight, or more or 

 less diagonally, or they may take a zig-zag and tortuous 

 path. The large granules are carried along rapidly in this 

 moving mass, while some granules can at times be followed 

 entirely around and then across the cell. 



Green light induces the formation of crystals of calcium 

 tartrate, and is unfavorable to the production of calcium 

 oxalate crystals. A very noticeable increase in the number 



