COMMON FROG. 97 



tinues very short, even in proportion to the diminutive size 

 of the animal (fig. 10). Meanwhile the anterior extremities 

 are also budding forth in the same manner, and gradually 

 assume their distinct and final form. 



As the hinder extremities become developed, the tail, the 

 former organ of progression, is removed by absorption, not 

 thrown off, as has been erroneously stated. This is a gra- 

 dual process, the absorption beginning at the apex, and pro- 

 gressing onwards to the base, until the whole is removed ; so 

 that the posterior part of tlie body becomes rounded, and the 

 cloacal opening, instead of being placed beneath, is directed 

 somewhat upwards. Fig. 1 1 exhibits the young Frog with 

 a small portion of the tail still remaining unabsorbed. 



Rusconi complains of having had considerable difficulty 

 in ascertaining the proper food for the Tadpoles, so as to 

 preserve them in health during his observations on their de- 

 velopement. He found, however, by accident, that they 

 would thrive upon the green sediment which results from the 

 agitation of decayed vegetable matter in water ; and I have 

 succeeded completely in keeping them on the decaying vegeta- 

 ble matter without any artificial preparation. In their more 

 advanced period, but still before the growth of the extre- 

 mities, they fed indifferently upon animal or vegetable sub- 

 stances, actually gnawing away the substance of almost any 

 kind of leaf that was placed in the vessel, as soon as it be- 

 came softened. I have reason to believe, also, that they 

 often killed their own companions as soon as these, by the 

 acquisition of their limbs, had nearly assumed their ultimate 

 form. Suspecting this, I placed in a large glass globe of 

 water, several Tadpoles, more or less nearly approaching 

 their final change, and I observed that almost as soon as one 

 had acquired its limbs it was found dead at the bottom of 

 the water, and the remaining Tadpoles feeding upon it. 

 This took place with all of them successively, excepting the 



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