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THE AMERICAN NATURALIST 



[Vol. LV 



some developed into distinctly living creatures, moving 

 about in the capsule on the fifth day after the setting 

 (Fig. 7) ; it took two weeks for the complete development 

 of the young. Alder and Hancock, 1845, p. 25, say : 



nhniii t.Mi .lays or a fortnight. 



Tcniix'iatiire, no doubt, plays an important part in the 

 speed i>\- (leveh)pmont. Stuart, 18()5, says: 



Daucr <l..r Kntu-i.-kdun- We.- Kmhrvo .in .Mnn.-u isl. iii ninuem Falle war 



'J'he second nidosome was to some extent abnormal, com- 

 l)ared with tlie first, and with those collected from the eel- 

 grass. It showed a variation of the number of eggs in 

 the capsules, from one to fifteen (Figs. 8 9). This abnor- 

 mality was perhaps an indication of the decline in vitality 

 of the mother animal. In fact, the adult specimen had 

 greatly decreased in size since its capture. 



One difficulty was that of keeping the water at a con- 

 stant (h'nsity. In order not to break the nidosome the 

 w;i1<'r u;is <uily exygonated and kept at a constant level. 



of the nidosome were removed, and by so doing the mem- 

 brane of the egg-})ody was broken. This did not seem to 

 affect the development, however. Yet it was thought 

 safer to keep the water at the same temperature as 

 hitherto, than to change it daily, as the latter might cause 

 too great physical shock. The abnormality of the water, 

 as said, did not affect the embryos as long as they were 

 within the capsules of the nidosome. Perhaps thus far 

 in their development they were not affected by the abnor- 

 inalit\- ol the water: e\en thoni;'!) the egg-body was punc- 

 tured and broken in the examination of the eggs, the 

 embryos seemed all to develop, as far as could be detected, 



