462 



ON THE EABLY STATE 



week in May. I have found, that the favourite 

 food of tadpoles, as soon as they are entirely de- 

 tached from the transparent globules, is the com- 

 mon duckweed, (Lemna gibbosa and minor) so fre- 

 quent in most ponds. They do not, however, refuse 

 other kinds of food. On one occasion, in particular, 

 I observed that several of their own species having 

 been wounded by the fierce larva 6f a large dystiscus, 

 were immediately attacked and devoured by their 

 more vigorous companions. The enormous crowds of 

 these creatures which may be seen in spring, has 

 often been a subject of wonder, more particularly 

 when they are considered in relation to the greatly 

 diminished numbers of the perfect animal. Few 

 out of the millions produced, ever attain maturity, 

 most of them serving as food to the different spe- 

 cies of aquatic insects. I once observed an aqua- 

 tic larva transfix and devour thirteen in the course 

 of a few hours. 



The tadpole state generally continues about two 

 months ; but I have found, that the period of 

 transformation is hastened by their confinement 

 within doors. The hinder legs are the first of the 

 external members which are perfected. In those 

 whose progress I attended to, they appeared about 

 the 8th of June. They are at first small and pen- 

 dant, and of no benefit to the animal in assisting 

 its locomotion. From that day to the 23d of the 

 same month, they continued to increase in size, and 

 upon the 24th, they were employed as organs of 



