II78 FAT METABOLISM [pt. iii 



the embryonic or larval body itself. This indicates that relatively much 



more protein is combusted than fat, as has been shown in Table 126. 



So far the eggs of the anuran branch of amphibia have alone been 



considered, but one chemical investigation exists which deals with 



those of a urodele, ihe giant salamander, Cryptobranchus allegheniensis. 



This is that of Gortner, to which attention has already been given in 



Section 9-9, We have seen above that the general consensus of opinion 



leads to the view that no fatty acids are lost from the egg of Rana 



temporaria up to hatching. But, if Table 1 69 is carefully examined, it 



will be seen that Bialascewicz & Mincovna observed an actual increase 



in fatty acids during the pre-natal phase. The increase was not great, 



being about 11 per cent., but, if they were there dealing with a real 



phenomenon, it was interesting, for a synthesis of fatty acids was 



found by Gortner to be important in the salamander egg. Gortner's 



facts were as follows (he did not follow the development further than 



hatching): 



Table 170. 



The loss of 1-66 per cent, of the dry weight was due to combustions to 

 carbon dioxide and water. "Accompanying this loss in weight", said 

 Gortner, "there is a very marked gain of fats equal to 3-06 per cent, of 

 the egg weight and to an increase of 1 4 per cent, of the fat already present 

 in the tgg.''' Gortner meant by "fat" the total ether extract dried to 

 constant weight, in which a number of other substances would be in- 

 cluded. It was not long before the fact of fat synthesis in this egg was 

 confirmed, by the aid of an accurate method. McClendon in the follow- 

 ing year applied the Kumagawa-Suto method to the same material. He 

 observed a numerically identical loss of dry weight between fertilisation 

 and hatching, and the figures for total extract compared as follows : 



Total ether- and alcohol- 

 soluble substances % 

 of the dry weight Increase (% ) 



Eggs Larvae Dry weight Initial 



Gortner 30-57 33'03 2-46 6-9 



McClendon 35-0 37-8 2-8 8-0 



