THE ABSORPTION OF FAT BY FRESH-WATER Ml -^KI.S. JI 



men ted with and of the control mussels were sectioned by the 

 freezing method, stained with Sudan III. and mounted in 

 glycerin. Also sections of the tissues of the adult and of the 

 entire bodies of the juvenile mussels were made after fixation 

 in osmic acid and Muller's fixing fluid. In this method the higher 

 alcohols were avoided by clearing the sections in clove oil from 

 85 per cent, or 90 per cent, alcohol and infiltrating in paraffin from 

 the clove oil. The paraffin was removed with xylol and the 

 sections were mounted in xylol balsam. Such sections were 

 studied very shortly after mounting, as the fat is gradually 

 dissolved out by the xylol. 



In some cases the fat solution was stained by dissolving Sudan 

 III. in the same to the point of saturation. The external appear- 

 ance of various parts of mussels which had been kept in such 

 stained solutions was noted. Also frozen sections of such mussels 

 were examined to ascertain whether or not stained fat had been 

 absorbed from the solution. In such cases the sections were 

 mounted in glycerin directly after cutting. 



OBSERVATIONS. 



The mussels were found to live readily in .001 per cent, to 

 .005 per cent, fat solutions. The only abnormal manifestation 

 to be observed was that a considerable quantity of mucus was 

 thrown off. Six adult individuals which were kept in fat solution 

 for one month w T ere living at the close of that period. At the 

 expiration of the same length of time one of the control mussels 

 of this experiment had died. After the adoption of the method 

 of manipulating the aquaria outlined above, no mussels died 

 while kept in fat solutions varying in strength from .001 per 

 cent, to .005 per cent. However, beyond the fact that mussels 

 can live for at least one month in fat solutions of these strengths, 

 no evidence was secured concerning the relative longevity of 

 those kept in fat solutions and of the control individuals. No 

 weights were taken. Experiments calculated to ascertain 

 whether or not the absorption of fat from the solutions employed 

 is of advantage to mussels were deferred until the actual entrance 

 of the fat into the tissues of the animal was proved. Emphasis 

 was therefore laid upon the histological evidence of the absorption 



