684 THE GENERATIVE ORGANS. 
of my sections. Such cells are, however, very difficult to 
identify in the general mass of granular material. 
Weismann [2] described the yelk of the newly-laid eggs of 
the Blow-fly as consisting of oil droplets and granules of im- 
measurable fineness suspended in a clear fluid, and was unable 
to find any germinal vesicle, which he says ‘ had already dis- 
appeared’ in recently impregnated eggs. (See Section 4, h. 
of this chapter.) 
4, ON THE DEVELOPMENT OF THE INTERNAL GENERA- 
TIVE ORGANS. 
a. The Earliest Appearance of the Gonads in the Embryo and Larva. 
The rudiments of the gonads, ovaries and testes are well 
known to appear, in mane insects, imbedded in the fat bodies't in 
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