DAPHNJAD^. 83 



it takes place in the young every two days, which agrees 

 very nearly with Jurinc's experiments, performed in the 

 month of June. In winter the intervals are somewhat 

 greater. In the month of December I found, when kept 

 in a vessel in my room, the intervals thus : December 8th, 

 young one born ; 12th, moulted for the first time; 14th, 

 moulted a second time; 17th, moulted a third time; 

 21st, moulted a fourth time, and has eggs ; 29th, moulted 

 a fifth time; January 9th, moulted a sixth time; 19th, 

 moulted for the seventh time. In a young D. pulex, born 

 from an ephippial egg, the intervals were as follow : 

 December 5th, young one born ; 13th, moulted for the 

 first time; 17th, moulted a second time ; 24th, moulted 

 a third time ; January 3d, moulted a fourth time, and has 

 eggs ; llth, moulted a fifth time ; 18th, moulted a sixth 

 time. 



Each time it moults it increases in size, the moulting 

 being evidently necessary for the gradual growth of the 

 animal. The process does not seem to stop, however, 

 when it has acquired its full growth, but, as far as I am 

 able to judge, continues during its whole life, even long 

 after it has gained its full size. The shell of the adult 

 Daphnise, when in very stagnant waters, soon becomes 

 overgrown with moss or parasitic infusoria, and thus 

 the animal's motions become much impeded, and at 

 last entirely destroyed ; the moulting, therefore, seems to 

 be necessary in the full-grown animal for the preservation 

 of its life, for weak or sickly individuals may be seen 

 frequently so overgrown with Confervse, &c., that motion 

 and life are both soon arrested, the little creature appa- 

 rently not having strength enough to throw off its exuviae. 

 At the fourth moulting* the young insect has eggs, which 

 are deposited in the open space on the back, almost im- 

 mediately after the old shell has been cast off. The time 

 that the eggs remain there varies according to the season 

 of the year. In summer, according to Jurine, three days ; 



* Straus says after the third ; Jurine, generally between the third and 

 fourth. I have invariably found it to be immediately after the fourth. 



