SECT. 8] 



CARBOHYDRATE METABOLISM 



1049 



c Glycogen in the silkworm egg 



a* Hibernation period 



glycogen disappearing. To these researches we must add that of 

 Kaneko, who noticed histochemically that at hatching no glycogen 

 was present in the silkworm embryo or its egg, a finding quite in 

 agreement with what has already been said. 



Rudolfs, using the egg of the tent-caterpillar, Malacosoma americana, 

 found a decline from 0-28 per cent, dry weight to 0-15 per cent, 

 during development. 



For echinoderm development we have only one complete piece 

 of work. Ephrussi & Rapkine 

 found for Strongylocentrotus lividus 

 that the unfertilised eggs had 

 5*43 per cent, total carbohy- 

 drate, the gastrulae 5-46 per 

 cent, and the plutei 3-4 per cent., 

 i.e. at o, 12 and 40 hours respec- 

 tively from fertilisation. The 

 corresponding wet weight per- 

 centages were 1-36, 1-35 and 

 0-72. It was therefore clear that 

 during the segmentation stages 

 no carbohydrate disappeared. Utilisation amounting to 50 per cent., 

 however, took place after the stage of gastrulation. The partition 

 between combined and free glucose was also interesting, as follows : 



oTichomirov 

 oVaney at,Conte 

 aPigorinI 



Fig. 290. 



Hours 



Non-glycogen and free glucose 

 Glycogen 



% of the total carbohydrate 



This state of affairs bears a resemblance to that found for the frog's 

 egg by Needham, as mentioned above. 



The glycolytic power of the sea-urchin's egg [Arbacia) has been 

 studied by Perlzweig & Barron. Measuring the lactic acid formed 

 under various conditions they obtained the following figures: 



Unfertilised control 



Unfertilised plus potassium cyanide 



Fertilised control 



2-8-cell stages control ... 



Mgm. lactic acid per gram of egg- 

 protein (experiments of varying 

 duration, mostly 3 hours) 



3-14 

 5-68 

 3-40 

 3-23 



67-2 



