Study of Spirogym nitida. 237 



and size of the tartrate crystals takes place by the fourth 

 day, and after this time a rapid decrease in the number of 

 oxalate crystals is observed. Many break into small pieces. 

 The diameter of the tartrate crystals is occasionally quite 

 as great as that of the cell. This peculiar variation pre- 

 vailed so long as the culture was maintained. 



No breaking down of the chlorophyll bands occurs, and 

 the healthy green color remains unaltered when the plant 

 is exposed to green light. But a flattening of the band, 

 with a corresponding increase in width occurs, and the 

 irreeularitv of the outline is so marked that the term 

 "amoeboid" may well be applied to it. In some cases the 

 bands run together so completely that it is difficult to dis- 

 tinguish any boundary line between the individuals. In 

 these bands the pyrenoids are remarkably distinct. They 

 are very refractive and larger than usual. 



Yellow. — A comparatively short exposure to yellow light, 

 that is two or three days, causes the green substance to become 

 much paler in color, and the bands show a slight tendency 

 to ball together. Under these conditions the starch rapidly 

 disappears, until by the close of the fifth day it is entirely 

 gone. The sugar, meanwhile, has increased far beyond the 

 normal amount. The cells, when treated with Fehling's 

 solution, become quite covered by the cuprous oxide result- 

 ing from the reaction. Although about five days are 

 required to free completely all the cells from starch, many 

 of them are emptied by the second day. 



While this conversion of starch into sugar is taking 

 place, there is a simultaneous and very marked growth in 

 the length of the cell. So rapidly does this elongation 

 take place that the chlorophyll bands are pulled out of their 

 spirals, and made to lie quite straight in the cell, which is 

 ultimately three times as long as when grown under white 

 light, though its diameter is not increased. 



These cells were tested repeatedly for tannin. In the 

 great majority of them none was found, though occasionally 

 a trace could be seen. 



