ZOOLOGICAL AND BOTANICAL ASSOCIATION. 9 



menced upon April 19th. On May 10th much green confervoid vege- 

 table matter having grown in B, I changed the water in both vessels 

 (although that in B' was quite clear and pure) and took the opportunity 

 of reckoning the tadpoles. I found still living, in B, 58; in B', 100 ; 

 no appearance of limbs on any of them ; many have little silvery marks 

 on each side of the middle line of the back, which on examination I find 

 to be little bubbles marking the first appearance of the lung. 



May 25th. I again, on account of a renewed growth of vegetable 

 matter in B, changed the water in both, and reckoned the number : in B, 

 five alive, large, healthy and active ; B', but one alive, not very large ; 

 no sign of limbs appearing on any of these. 



June 21st. In B, five still alive, healthy and active; in B', one still 

 alive, and healthy ; no sign of limbs. 



Angust 1st. In B two continue to live, as large, healthy tadpoles, 

 showing no signs of further development. Both died undeveloped in the 

 course of the month of August. 



The one in B' died in the end of June. 



Seventh Experiment. — Two glass jars of the same form and capacity 

 as those used in the first experiment, were filled with fresh water and 

 100 tadpoles put into each; one (C) was placed in the window; the 

 other (C) in darkness in the inside of a large chest ; in both, the tad- 

 poles were fed with portions of the flesh of frogs, which they ate vora- 

 ciously; besides, in that which was submitted to the light the confervoid 

 vegetable matter afforded abundant food. This experiment was com- 

 menced April 19 th. 



May 10th. The confervoid vegetable matter has grown so abundantly 

 in the vessel (C) in the window, that the water in it, as well as in C, 

 was changed, and the tadpoles reckoned : in C, 60 alive; in C, 100. No 

 sign of commencing transformation in any. 



25th. The water was again changed on account of the growth of ve- 

 getable matter. In C, 29 alive and healthy ; in C, 36 alive, of various 

 sizes, but even the smallest healthy and active. No sign of commencing 

 transformation. 



June 21st. Water again changed: in C, 4 alive ; in C, 7 alive : one 

 of those in C has the posterior links just beginning to appear. 



August 1st. Of the four tadpoles in C, at last report, one died unde- 

 veloped; one of large size was this day taken to be preserved ; 2 under- 

 went complete development into frogs, and lived for some time as frogs, 



ZOOL. & BOT. SOC. PBOC. — VOL. I. C 



