OF THE TADPOLE. 29 



Soft vegetable matters seem to be equally agreeable to their 

 palate with decomposing animal substances, a little bread or 

 biscuit appearing very acceptable, after it had become quite 

 macerated in the water. That they possessed a discerning taste of 

 their own, was seen by the manner in which they fed with avidity 

 from a sweet biscuit, whilst they more or less rejected another 

 containing no sugar ; indeed, it is possible to retain these animals 

 in apparent perfect health by feeding them entirely on sweet 

 biscuit, leaving them to obtain their own animal food in the best 

 manner they can. In a tank where many are congregated toge- 

 ther, some are certain to die, and in this case the survivors invari- 

 ably leave any food they may be eating to attack the dead bodies 

 of their friends, which are much more juicy and succulent than the 

 majority of the food usually given to them. 



From the loth of April, the animals in the vessel containing 

 much vegetable matter, were found constantly exploring the sides 

 of the glass tank, pressing their noses, or rather the frontal-nasal 

 process which protrudes as a kind of band over and beyond the 

 head, so vigorously against the glass as to remove the algae grow- 

 ing on it, in lines, so as to produce a number of minute furrows 

 often extending upwards for several inches. In working off this 

 material from the sides of the tank, the general tendency of 

 motion was from below towards the surface, although scarcely ever 

 in a truly vertical direction. For some time, I was of opinion that 

 they were engaged in eating the whole of the material thus 

 ploughed off, as during ,the process, the mouth could be seen 

 working most energetically, opening and shutting several times 

 per second. 



A microscopical examination of this green material showed it to 

 consist of the most heterogeneous mixture, much of it being pro- 

 tococci mixed with minute cells of a linear algre, as well as with 

 numbers of amoebiie, and crowds of minute animals of all descrip- 

 tions, both living and dead. A large quantity of this green matter 

 was in a decaying state, and all as soft and succulent as possible, 

 so that when disengaged from the glass the animals could readily 

 suck it into their mouths, no teeth being required to tear it in 

 pieces, as it was already in the most comminuted form possible. A 

 microscopical examination of the faeces of these animals showed 



