THE ABSORPTION OF FAT BY FRESH-WAT]-: R Ml KLS. 73 



sections. The former all presented abundant evidence of the 

 presence of fat. The difference between those which had been 

 kept in the solutions and the control mussels was as striking as 

 that shown in Figs, i and 2. 



The best results were obtained from the study of juvenile 

 mussels as in these cases the entire animal could be sectioned 

 serially and the distribution of the absorbed fat over the entire 

 body observed. A specimen of Anodonta imbecillis which had 

 been kept in .002 per cent, fat solution for 10 days and a control 

 specimen of the same species which had been kept in filtered 

 water for the same length of time were selected as typical cases 

 for study. 



Figs. 4 and 5, PI. II., showing corresponding parts of the foot, 

 give an idea of the abundance and distribution of fat in the mussel 

 which had been kept in the fat solution and of the almost entire 

 absence of it in the case of the control specimen. (In this case 

 as well as in that of several of the other figures, no effort has been 

 made to draw the outlines of the epithelial cells, the intention 

 being merely to represent the relative amount and distribution 

 of the fat.) It will be noted that the fat is very abundant in 

 the epithelium. It is present in some quantity in the interior 

 of the folds of the foot and also within the deeper parts of the 

 foot, apparently adhering to muscle fibers. The fat droplets 

 exhibit some tendency here, and more markedly elsewhere, to 

 gather together in clumps or to form chains. Several blood 

 corpuscles which contain fat may be seen. 



Fig. 6, PI. II., shows a portion of the foot of the same indi- 

 vidual, extending from the base of a fold to the blood vessel in 

 the center of the foot. An abundance of fat was observable in 

 the epithelium and quite numerous droplets appeared clinging to 

 muscle fibers or enclosed within corpuscles in the central part 

 of the foot. 



Fig. 7, PI. II., representing a portion of a fold of the foot, was 

 drawn under the 1/12 oil immersion lens, an effort being made 

 to depict the exact number and position and also the relative 

 size of the fat droplets, muscle fibers and cells. 



Fig. 8, PI. I., shows in (a) the cross section of a liver tubule of 

 the mussel used as the control, the few coarse stipples represent- 



