STICKLEBACK'S NEST. WATER FLEAS. 173 



with water, were of such gravity as to prevent their rising. He 

 deposited these with great care, leaving a perfectly round hole 

 in the middle, and then having procured a mouthful of sand, 

 laid it over the looser materials to cement them together. 



" When completed, the nest resembled a flattened haycock. 



" For about a week after this completion it seemed deserted. 

 But one morning it was found that some eggs had been laid. 

 These for the size of the fish are very large, being about the 

 size of a middling-sized shot. They hatched in about from 

 ten days to a fortnight, the young fish remaining in the nest 

 until the yolk-Dag was absorbed, when, being large enough to 



WATER-FLEAS 



AMMALCULJE IN DROP OF WATER, 

 AS SEEN UNDER THE MICROSCOPE. 



look after themselves, they went their way. The parent who 

 had so tenderly guarded them took no further heed of them, 

 and himself died such being the case in both instances which 

 came under notice, both parents sickening and dying from the 

 effects of spawning and watching, or perhaps from the aquarium 

 not being fitted for their recovery/' 



Those who keep aquaria in an intelligent manner and 

 study the habits of the creatures they imprison, will find it 

 both interesting work, and a never-failing source of amuse- 

 ment It is very little trouble. When the water is put in, and 

 the plants begin to grow, the water need not be changed. The 



