244 Pennington — A Chemico-PJiyswlogical 



paring for conjugation. Actual conjugation was not, how- 

 ever, attempted. 



The quantity of sugar and tannin is very small, the 

 latter constituent occasionally entirely disappearing from 

 some of the cells. Crystals of both kinds could be detected. 



Yellow-orange g-lass. — This glass, while it permitted 

 the passage of all the orange and part of the red, gave 

 results which were strikingly like those obtained under 

 pure yellow, though the time required to produce them 

 was much lengthened. 



The starch disappeared about the ninth day, and the cells 

 were then filled with sugar and were very long. The 

 tannin, unlike the pure yellow culture was in large quantity. 

 No crystals could be seen in the long cells, and the chloro- 

 phyll was in rather a bleached condition. The bands here 

 lie straight in the cells just as do those in yellow light. 

 Treatment with iodine in potassium iodide causes the same 

 rupture of the cell wall. 



It was stated that under the blue glass no bending of the 

 filaments took place, even though these rays are so posi- 

 tively heliotropic in their action. Under the yellow-orange 

 screen the threads were bent sharply upon themselves, as 

 many as five distinct folds being assumed. Since the rays 

 which this glass transmits are supposed to be almost with- 

 out heliotropic action it may well be asked, Are not these 

 folds due simply to the weight of the long weak threads ? 

 The plant under the blue screen was made up of short, 

 strong cells, and the filaments were short, as compared with 

 the long filaments under the yellow. This may account 

 for the fact that no bending occurred under the blue. 



Behavior of the Cells in Darkness. 



Some endeavors to de-starch Spirogyra nitida by simply 

 placing it in the dark produced rather peculiar results, 

 which led to a more careful study of the behavior of the 

 plant when all light was excluded. It was found in this 

 preliminary work, that the threads did not de-starch readily, 



