ABSORPTION OF NUTRIMENT BY MUSSELS 409 



were prepared both by the paraffin and by the freezing methods 

 and efforts were made to detect starch in the cells by staining 

 with iodine. Mussels were also kept in solutions of starch which 

 had been colored blue with iodine. Spring water was used 

 in this case as the tap water contained so much free chlorin 

 that the blue color was removed from the solution. 



Further details of the methods employed will be stated in 

 connection with the observations recorded below. 



OBSERVATIONS 



Fat 



The solutions made from the commercial soap were found 

 to be more satisfactory than those used in the previous work 

 with fat where olive oil was saponified with sodium hydroxide. 

 In the solutions from the latter the mussels were found to throw 

 off much mucus, no doubt owing to the free alkali present due 

 to a slight excess of sodium hydroxide employed in the process 

 of saponification. 



The mussels threw off no appreciable amount of mucus while 

 in the solutions prepared from the non-alkaline commercial 

 soap. None died while in the solutions. There was no evidence 

 of any toxic effect due to the soap solution. 



The results were the same as those obtained in the previous 

 work with fat. The mussels which had been kept in the solu- 

 tions were found to contain much more fat than those not so 

 kept. This fat was distributed in the form of droplets^ in greater 

 or less abundance in nearly all parts of the body. Figures 

 1, 2 and 3 represent portions of a specimen of an adult Quadrula 

 ebenus which had been allowed to remain in a 0.002 of one per 

 cent soap solution for five days. The fat, represented in the 

 drawing by the heavy black dots, may be seen in the epitheUal 

 cells of the gill filaments, the ostia, the water tubes and in the 

 corpuscles. 



' The term 'droplets' will in this paper be applied to the spherules of ab- 

 sorbed fat found in the tissues of the mussels experimented upon. These drop- 

 lets usually were of diameters varying from less than one micron to 3 or 4 microns, 

 though instances were found in which the diameter was as great as 7 or 8 microns. 



