504 PARENTAL CARE AMONG FRESH-WATER FISHES. 



loreniost into the nest and bring out a mouthful of mud, which it would carry 

 to some distance and discharge with a puff. 



The third day was passed in much the same manner, only as the eggs were 

 now all hatched the nest was less frequently fanned or ventilated, and the fry, 

 about 40 in number, were allowed greater liberty, the strongest being permitted 

 to recreate themselves among the conferva? that grew on a stone al)out 2 inches 

 from the nest. On the fourth day the fanning had ceased altogether, and the 

 rambles of the young were less restricted. They were not yet, however, permitted 

 to pass beyond certain limits. When any transgressed these bounds they were 

 immediately seized as heretofore and carried bacli to the nest, into which they 

 were always very glad to escape from the clutches of their ardent parent. 

 Notwithstanding all her vigilance one contrived, on the fifth day, to escape her 

 eye, and in passing the fateful boundary was immediately devoured by the 

 other fish, which now seemed always on the watch, neglecting its own barren 

 nest, being intent only on appropriating to itself the nestlings of its fruitful 

 neighbour. In this act of cannibalism we see the reason for the parent's anxious 

 care and its jealousness of its kind ; and it is evident from Mr. Crookenden's 

 account, previously quoted, that they greedily devour each others spawn. The 

 young fry, however, have other enemies as well as their own species. One day 

 a favorite Hydra (H. fusca) was observed to be distended in a most extraordi- 

 nary manner. On examination it was found to have swallowed the head and 

 shoulders of one of the young fish many times larger than itself, and the caudal 

 extremity, which was too much for it and which was projecting out of its mouth, 

 had been seized upon l\v another Hydra. Thus it would appear that these low 

 organized but powerful and voracious animals occasionally regale themselves 

 on the flesh of the Vericbnitu. This happened when the fry were three or four 

 weeks old. 



All the old fish, with the exception of that with the young, were, in conse- 

 quence of their cannibal propensities, turned out of the trough ; and danger 

 being thus removed, the fry were no longer restricted in their rambles, but 

 enjoyed the whole range of their crystal abode. Henceforth the parent's assi- 

 duity gradually relaxed, though for days afterwards it was its custom to 

 take the young occasionally into its mouth, and after carrying them a little 

 distance to let them drop out again. I took one of the fry out one day for 

 examination with the microscope. On returning it to the trough it was in so 

 sickly a state as to be scarcely able to leave the vessel, which was held in the 

 hand. The old fish, perceiving the helpless condition of its offspring, came up 

 to the surface of the water, and seizing hold of the exhausted young one car- 

 ried it off almost from amid my fingers, and taking it to some distance puffed it 

 out of its mouth into a tuft of confervse. This courageous act of our little fish 

 would seem, in some measure, to give credence to the assertion, so frequently 

 made, that some of the sharks protect their young by receiving them into the 

 mouth on the approach of danger. 



The stickleback's life is probably a short one. For a long time it 

 was supposed to be biennial, but one individual at least was kept for 

 " nearly double that time." 



Such are the habits of the three-spined stickleback. Those of the 

 other species of the family are similar in most respects, but each group 

 of species seems to have its own' special way of making its nest, as 

 Coste long ago (1848) showed. According to the French naturalist, 

 while the three-spined sticklebacks (Epinoches) invariably (invari- 



