Mr. R. Warington's Notes on Animals in small Aquaria. 367 



isms by the introduction of the water-snail or other phyto- 

 phagous mollusk, as I have elsewhere described*, I may state 

 that the same water in which my original experiments were made 

 in March 1849 has been in continual use up to the present time, 

 several fish living constantly in it, without disturbance, and that 

 it is now as bright and in as healthy a state as at the first period 

 of its being employed. 



Again, in a small jar of about one pint capacity, having a 

 single plant of Vallisneria spiralis growing healthily in it, and 

 with a few small water-snails as scavengers, I succeeded during 

 the spring of 1853 in hatching and rearing a young trout. 

 The egg was obtained from Mr. S. Gurney, jun., and had been 

 removed from his preserves in the river Wan die ; the shell 

 ruptured the day after my receiving it, and it was maintained 

 in a jDerfectly healthy state during the whole of the period 

 required for the development of the respiratory organs, and 

 the complete though gradual absorption of the ovum. This 

 development was perfected in fifteen days from the bursting of 

 the shell, till the period that the fish could sustain itself con- 

 tinuously in the water and was able to swim strongly. Having 

 arrived at this stage of maturity, the vessel became far too small 

 for the free use of its active powers of locomotion, and it was 

 therefore transferred to a small tank containing several minnows, 

 when to my great annoyance it was immediately seized and de- 

 voured. 



As another instance of the voracity of the finny tribe and 

 their destruction of each other, I may mention here that I 

 had on a previous occasion placed several small trout fry over- 

 night in an aquarium containing some gold-fish, but they must 

 have been rapidly preyed upon, as no trace could be seen of them 

 the following morning. These facts will demonstrate clearly the 

 havoc which must take place in the rivers and streams among 

 the young fry of various fish under ordinary circumstances, when 

 they are proved to be devoured with such extraordinary rapidity 

 even by such species as the gold-fish or carp tribe and the 

 minnow. 



Memorandum 3. 



Care should be taken in the aquarium for fresh water to ex- 

 clude the ordinary Polype or Hydra fusca, particularly where 

 certain species of fish are to be preserved, as with the minnow 

 (Leuciscus Phoxinus), for these creatures, insignificant as they 

 may appear, after a short time cause their death, and that under 

 most extraordinary circumstances, as the following observations 



* Quarterly Journal of the Chem. Soc. for April 1850, vol. iii. p. 52. 



