Study of Spirogyra nitida. 245 



even when, so far as could be determined, the plant grew 

 in perfect darkness. A quantity of fresh threads placed in 

 a beaker glass, and covered with tap water, the whole 

 being maintained in darkness, showed in the cells very 

 appreciable amounts of starch even after two weeks had 

 elapsed. The condition of the cells at the expiration 

 of this time was not very good. Here and there the bands 

 had lost their normal positions, and in some a distinct 

 breaking down of the cell could be seen. By the time the 

 starch had been converted into soluble products the cell 

 was so altered in other respects that it was quite useless 

 for physiological experimentation. 



In these darkened threads a solution of the crystals was 

 very apparent. They broke down into small fragments, and 

 were finally dissolved as under the action of yellow light. 

 This solution became more rapid as the amount of starch 

 grew less, but in no case were the crystals wholly used up. 

 Since starch-free material was much needed for experi- 

 mental work it became necessary to find a method by which 

 this end could be gained, and still have comparatively 

 healthy cells. It was thought that running water might 

 perhaps prevent decomposition and enable the cells to 

 survive until all the starch had been metabolized. Accord- 

 ingly a small stream from a laboratory tap was led into a 

 jar containing the plant, and the whole covered with a tight 

 box. At the end of twenty-four hours scarcely a trace of 

 starch was found in the cells which were otherwise perfectly 

 normal. Thirty hours will suffice to remove all the starch 

 from Spirogyra nitida, while the more slender species 

 react even sooner. 



To determine whether this result was due to the plenti- 

 ful supply of inorganic salts furnished by the running 

 water, a quantity of the plant was placed in distilled water 

 to which a culture mixture was added. The starch was 

 removed very slowly, and the cells behaved as they did in 

 a limited supply of tap water. The inorganic salts, then, 

 are not responsible for this behavior. 



