98 UANAD^S. 



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 re- 

 servoir of eggs in a very cold situation, and occasionally 

 brought a few of them into my drawing-room for the pur- 

 pose of observation ; in which place, being in an elevated 

 temperature, the developement became very rapid. As my 

 object, therefore, was to ascertain positive facts, rather than 

 the periods of the changes, which were dependent upon 

 variable circumstances, I kept no register of the tempera- 

 ture or of the periods ; and I shall, in both these par- 

 ticulars, give some of the statements of the accurate 

 Rusconi. 



The embryo is found, in the first place, to consist of a 

 small globular body, one side, or hemisphere, of which is of 

 a dark brown colour, the other being much paler. In a 

 very short period after the egg is deposited, four hours, 

 according to Eusconi, a deep furrow across the dark hemi- 

 sphere divides it into two equal parts, and this is soon 

 afterwards crossed by another at right angles ; a third and 

 a fourth furrow are produced, and so on, until the whole 

 surface of this side of the sphere is, as it were, granulated. 

 This appearance, however, is but transitory, the surface 

 soon becoming almost smooth. In the course of the second 

 day, the sphere begins to elongate, and a groove, which 

 had previously divided the upper part of it into two equal 

 parts, begins to close up. The head becomes prominent, 

 the tail begins to shew itself, the little hooks by which it 

 subsequently lays hold of objects and supports itself, begin 

 to appear. At this period the examination becomes more 

 easy, and more interesting. At somewhat more than fifty 

 hours in an elevated temperature, the head is very well 

 marked, the tail somewhat elongated, and even the rudi- 



