418 E. p. CHURCHILL, JR. 



The above results demonstrate that the cells of the outer 

 body walls of the mussels have the power to absorb at least 

 one protein, albumin, from the surrounding solution. 



Starch 



Soluble starch was made by boiling commercially prepared 

 cornstarch in water. One gram of starch was used in about 

 400 cc. of water. The solution, after boiling, was allowed to 

 settle and 50 or 100 cc. of the supernatant liquid used in making 

 the solutions in which the mussels were to be kept. This method 

 affords only a rough estimate of the amount of starch present, 

 as the amount of starch that went into solution was not deter- 

 mined. However, qualitative results only were sought in these 

 initial experiments. The supernatant liquid was proved to 

 contain starch by testing with iodine. After the mussels had 

 remained in the solutions for various lengths of time they were 

 killed and sections of their tissues were made both by the freez- 

 ing and by the paraffin methods. The sections were then placed 

 in alcoholic solutions of iodine for different periods of time and 

 an effort was made to find blue granules within the cells. The 

 results were negative. The tissues as a whole often assumed 

 a slight yellow tint from the influence of the iodine, but no gran- 

 ules were found that could be considered to have a blue color. 

 As iodine stains dextrin or causes it to assume a red color, search 

 was made for red particles in the cells. It was thought possible 

 that the starch might have been more or less completely con- 

 verted to sugar by the cells and that evidence of some of the 

 incidental steps could be found. Very small red granules were 

 found both in the tissues of the mussels which had been in the 

 solutions and in those of the controls. These red particles 

 were no doubt the pigment granules which impart to the tissues 

 the pinkish hue observable in many specimens of Quadrula 

 ebenus. They presented no difficulties in the work with fat 

 which had been stained red with Sudan III, as the pigment was 

 in the form of small, irregular, highly refractive granules readily 

 distinguishable from fat droplets. Their presence offered some 



