The Life-Cycle of Cladocera. 



427 



relative to reserve storage with the occurrence and non-occurrence of the 

 sexual forms ? 



An examination of the condition of the sexual forms strongly suggests that 

 an affirmative answer can be given to this question. The ephippial females 

 are always bright orange in colour owing to the abundant presence of fat in 

 all the subdermal tissue at the sides of the gut and at the bases of the limbs, 

 while the ephippial ovary is characterised by the presence of closely packed 

 globules of fat in the eggs and nurse cells. The appearance of an ephippial 

 female with its abundant reserve fat and opaque ovary loaded with fat is shown 

 in fig. 7. In contrast with this the parthenogenetic female, even under the 



Fig. 7. — An ephippial or sexual female with ephippium of two egg chambers and 

 opaque ovary full of fat. The reserve material present is in the form of very 

 numerous fat globules of an orange-red colour. 



crowded condition at low temperature, never exhibits so much fat in its 

 reserve deposits, while the parthenogenetic ovary contains a very large 

 quantity of amylaceous matter in addition to the comparatively sparse large 

 fat globules in it. The adult males, as shown in fig. 8, resemble the ephippial 

 females in the abundance of fat present as reserve substance. 



Another point to be noted is that the ephippial females are inhibited in their 

 growth and never attain to the same size as the parthenogenetic females kept 

 isolated at 27° C, while the males are even more stunted. 



We thus see that there is a remarkable coincidence between storage of 

 glycogen and rapid growth on the one hand, and fat-storage and inhibition 



VOL. LXXXV1II. — B. 2 L 



