COMMON FROG. 97 



during its passage. When first expelled it consists of nu- 

 merous small opake globular bodies, enveloped in a small 

 glairy, or glutinous mass. This latter substance soon ab- 

 sorbs a large quantity of water, and, in the course of an 

 hour or two, each becomes not less than a quarter of an 

 inch in diameter. The consequence of this augmentation 

 in the bulk of the transparent mass, surrounding each em- 

 bryo, is, that all the latter are removed from each other by 

 a whole diameter of each globe ; and they appear like black 

 dots regularly distributed throughout a large mass of trans- 

 parent jelly. 



The deposit of the eggs takes place at the bottom of the 

 water, notwithstanding the assertion of some naturalists, 

 and of Rosel amongst them, that they are expelled at the 

 surface. The mistake, probably, arose from the mass of 

 eggs being generally found at the surface ; but this arises 

 merely from the disengagement of gas in the substance of 

 the glairy envelope, in consequence of partial decompo- 

 sition. 



The changes which now begin to take place in the em- 

 bryo are most interesting. They have been detailed in a 

 very minute and satisfactory manner by Rusconi in his 

 work, already alluded to ; and I have taken considerable 

 pains during the last spring to follow out his investigations, 

 and by actual observation to correct or confirm his account. 

 I may here observe, once for all, that, with the exception 

 of a few of the details in the earliest periods, I have been 

 able to satisfy myself of his correctness ; and in those 

 points, I believe that I only failed to do so, partly by my 

 not having obtained the ova immediately after their expul- 

 sion , and partly by the want of time to enter into all the 

 necessary minutiae of the investigation. 



I have also to observe that the developement of the young 



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