Study of Spirogyra nitida. 24 1 



crowded closely together, almost or quite hiding the 

 nucleus from view. This piling up of starch was not at 

 the expense of sugar, the presence of which was always 

 demonstrable, and in quantities agreeing with the normal. 



The tannin formation was excessive. Copper acetate 

 threw down a heavy precipitate in the cells, and ferric 

 chloride colored them inky black. 



The crystals, on the other hand, were not so many nor 

 so large as when grown in white light. Eight days caused 

 a breaking down of oxalate, while by the tenth day very 

 few of these remained. Calcium tartrate crystals were not 

 many, but here and there one did survive. These, when 

 solution took place, had the arms dissolved first, leaving 

 behind a square plate which was at first mistaken for 

 another variety of crystal. In time these likewise dis- 

 appeared. 



The protoplasm seemed to be normal in every way. The 

 nucleus, when it could be distinguished in the dense mass 

 of starch-laden chlorophyll bands, was very refractive, but 

 contained dark particles as usual. The nucleolus was also 

 very refractive. 



These cultures, like the orange, can be kept for an in- 

 definite period in good condition. The growth is even more 

 rapid than in white light. 



Growth Under Colored Glass. 



Having carefully cultivated and watched the develop- 

 ment of the plant under pure light, some experiments car- 

 ried on under colored glasses may well be compared with 



them. 



The apparatus was the same as that used by Macfarlane* 

 in his "color screen" experiments on the sensitive plants, 

 and consisted of a square wooden frame, into the sides and 

 top of which were fitted glass plates of the desired color. 

 The healthy Spirogyra was grown in white glass jars hav- 

 ing a capacity of about one litre. These were placed 



*Bot. Central. Vol. 61. 



