Study of Spirogyra nitida. 235 



but apparently otherwise unchanged. Later the cell-con- 

 tents balled together as before, but now treatment with 

 iodine solution did not cause any bine-violet color. The 

 organisms above mentioned promptly attacked the cell, 

 which, weakened from starvation, succumbed to their 

 ravages in about four days. During this time no starch 

 formation could be detected. 



IJIue. — The phenomena observed, when the plant was 

 grown under blue light, were exceedingly interesting and 

 suggestive, when compared with the results obtained with 

 bands from other parts of the spectrum. 



For five days after submitting Spirogyra to the action of 

 blue rays the cells were, morphologically, in good con- 

 dition. The starch grains were slightly diminished in size. 

 Chemical examination showed that sugar was in much 

 smaller quantity than that normally present. 



At this time the protoplasm was seen to take on a gran- 

 ular appearance, which grew constantly more marked. 

 By the seventh day the chlorophyll bands had lost their 

 characteristic disposition in the cell and had become some- 

 what balled, though not to such an extent as those under 

 violet light. The pyrenoid centres, with their surrounding 

 starch granules, were scattered promiscuously over the cell, 

 while here and there the dense granular protoplasm could 

 be seen between the green masses. Treatment with iodine 

 caused the starch grannies to become deep bine, while 

 the dense protoplasm assumed a rich red-violet color. 



When Fehling's solution is used we find the areas 

 corresponding to the red-stained protoplasm precipitating 

 cuprous oxide. 



Exposure to blue light pushes metabolism a step ahead 

 of that obtained under violet light. There is sufficient 

 energy here to produce a reducing carbohydrate, and one 

 also which can be assimilated by the cell. The blue ravs, 

 like the violet, cannot produce starch. But starch hydro- 

 lysis is possible, though the process is so slow that the 



granules originally present become from day to day almost 

 16 



