410 E. p. CHURCHILL, JR. 



Mussels were kept in soap solutions stained with Sudan III. 

 A gill filament of such a mussel after it had remained in the 

 solution for five days is shown in figure 4. Pink or orange 

 colored fat droplets were found in great abundance in the epithe- 

 lial cells of the filaments, ostia, water tubes and in the corpuscles. 

 This fact furnishes direct proof that the heavy loading of fat 

 found in the mussels which had been in the soap solutions was 

 not due to the chance use of an extraordinarily fat individual. 

 The colored fat could have come only from the stained soap 

 solution. 



Mussels with the valves wedged open were suspended over 

 the solutions in such a manner that only the lower edges of the 

 mantles were immersed in the solutions. The animal soon re- 

 laxed the foot so that the end of that organ also was covered. 

 Control individuals were suspended in like manner over filtered 

 water. The experiment was continued for forty-eight hours. 

 Numerous fat droplets were found in the cells of -the parts of 

 the mantles and foot which had been immersed in the solution 

 and none were discovered in similar tissues of the controls. 

 Epithelial cells of the mantles and foot that had been covered 

 by the solution are represented by figures 5 and 7, while figures 

 6 and 8 show cells of corresponding parts of the control muscles. 



It was thought possible that in this case the presence of fat 

 was due to fatty degeneration incident to the weakened or mori- 

 bund condition in which the mussel might be supposed to be 

 after having been suspended thus with the larger portion of its 

 body in the air for forty-eight hours. Such a supposition was 

 rendered negligible by the facts that the mussels in which the 

 fat was found were apparently in a healthy condition when 

 killed ; that no fat was found in the controls and none in mussels 

 which had been allowed to die while so suspended over filtered 

 water. 



Finally, a large mussel with the valves wedged open was placed 

 over the edge of the aquarium in such a manner that the lower 

 edge of one mantle only was immersed in the soap solution, 

 the entire remainder of the body being in the air. After a 

 period of forty-eight hours sections of the part of the mantle 



