92 RANID.E. 



water, notwitlistanding tlie assertion of some naturalists, and 

 of Rosel amongst them, tliat 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 en- 

 velope, in consequence of partial decomposition. 



The changes which now begin to take place in the embryo 

 are most interesting. They have been detailed in a very 

 minute and satisfactory manner by Rusconi in his work, al- 

 ready 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 

 is more or less rapid, according to the temperature of the 

 atmosphere ; and that I was enabled to retard or hasten it by 

 regulating this circumstance. I therefore kept my reservoir 

 of eggs in a very cold situation, and occasionally brought a 

 few of them into my drawing-room for the purpose of ob- 

 servation ; in which place, being in an elevated temperature, 

 the developement became very rapid. As my object, there- 

 fore, was to ascertain positive facts, rather than the periods 

 of the changes, which were dependant upon variable circum- 

 stances, I kept no register of the temperature or of the pe- 

 riods ; and I shall, in both these particulars, give some of 

 the statements of the accurate Rusconi. 



