i82 FAT METABOLISM [pt. iii 



Table 173. 



Iodine no. Saponification no. 



Embryo Em- 

 (without bryonic 



Liver Ovary Muscle Yolk liver) liver Liver Ovary Yolk 



"Spring-torpedo" i20 44 47 129 — — i95 — 186 



"Summer- torpedo" 122 42 — 140 38 65 — — — 



"Autumn-torpedo" loi 153 43 — — -~ '93 '53 — 



From this it appears that the fat of the embryonic body has a low 

 iodine value, about the same as that of the adult muscles, but that 

 its Uver fat has one twice as high. The yolk fat is twice as unsaturated 

 as that of the avian egg-yolk. Its presence in the ovaries of the 

 "Autumn-torpedo" accounts for the high value found then. 



Another selachian, Centrina vulpecula, was studied by Kollmann, 

 van Gaver & Timon-David who obtained the following constants 

 from a specimen which seemed to contain in its abdomen practically 

 nothing but eggs and liver : 



This agrees well enough with the results of Reach & Vidakovich 

 in that the egg oil is particularly unsaturated, cf the state of affairs 

 in the hen's egg, and the value of ready-made double bonds to the 

 embryo. Apparently the fatty acids of the yolk in this fish have as 

 long chains as those of the liver. 



Similar work was done on Centrophorus granulosus by Andre & 

 Canal, who obtained the following figures : 



Composition of the crude oil % 



Crude oil ,- '^ ^, 



in % of Fatty acids 

 wet (principally 

 weight clupanodonic) SqUalene Cholesterol 



Egg ■•• 29 45-5 55-1 4-7 



Foetal liver 56 32-0 66-0 3-8 



Liver of immature female 78 15-8 840 i-6 



Liver of adult female ... 85 82 91-0 i-o 



They naturally concluded that during ontogeny there was a pas- 

 sage from clupanodonic glycerides and cholesterol to squalene, a 

 passage which was traversed in the opposite direction during the pre- 

 paration of the eggs by the adult female. Squalene seems to play an 

 important part in selachian metabolism (see p. 350). 



