214 



The eggs are quite as large a month or two before spawning 

 as when they are extruded, and during this time when they are 

 maturing it may be that nutrition is no longer necessary, and 

 would explain the rise in glycogen just before the spawning 

 period. This, along with the apparent absence or slo\\^less 

 of a diastatic enzyme suggests that the glycogen stored up 

 by the sea mussel is made direct use of in the extraordinary 

 reproductive activity of this animal. 



Fat. 



The amount of fat, as we have already seen, is small, and 

 shows a steady increase up to the time of spawning. The 

 accumulation of fats throughout the year is well shown both in 

 frozen sections stained with Sudan III, and in tissue fixed in 

 Fleming without acetic acid. Sections in October show fat 

 only in certain liver tubules, and intestinal epithelium. This 

 increases in amount, and by November the fat is beginning to 

 show in the growing reproductive products in the body and 

 mantle. From December onwards there is an accumulation of 

 fat about the sperm sacs of the males, and in the eggs of the 

 females, and this condition obtains until the spawn is extruded, 

 after which time the fat again seems restricted mainly to the 

 liver. 



Enterochlorophyll. 



The greenish yellow pigment extracted from the digestive 

 gland of several molluscs by MacMunn*, and named by him 

 Enterochlorophyll, is very evident in frozen sections, and 

 also attracted attention during the extraction of fats in the 

 Soxhlet apparatus, by giving to the carbon tetrachloride a deep 

 green or bro^vn colour, until the apparatus had siphoned over 

 several times. It was noticed too that after a Pfliiger glycogen 

 estimation the pigment showed itself in the filtered liquid, 

 and had therefore apparently resisted digesting on the water 



* MacMunn, loc. cit., p. 235. 



