58 J. T. PATTERSON. 



been experienced in cutting the moth eggs into sections from 

 three to five microns thick. Preparations of the entire egg 

 have also been used in the study of maturation. These were 

 made from smears of the host egg. 



THE FRESHLY DEPOSITED EGG. 



The freshly laid egg of Paracopidosomopsis is a pear-shaped 

 cell, very similar in appearance to that of Litomastix, as figured 

 and described by Silvestri ('06). Different eggs vary consider- 

 ably in size, and to some extent also in shape. In Fig. 2 is 

 shown a typical egg some time after it had been deposited. The 

 average egg measures about 115 /j. in its long axis and 60 /x at its 

 widest diameter. 



The egg may be divided into two parts, the anterior portion 

 or pointed end, and the posterior portion or broad end. At the 

 time of deposition there is no line of demarcation between these 

 two parts, but after the beginning of cleavage they are recognized 

 as the polar region containing the polar nuclei, and the embryonal 

 region consisting of the true embryonic cells. 



The egg is surrounded by a thin but tough membrane, prob- 

 ably a true chorion. It is also possible that a very delicate 

 vitelline membrane is present, although this is difficult of demon- 

 stration. 



The contents of the egg consists of a very finely granular 

 protoplasm in which are found a few scattered yolk or oil spherules 

 (Fig. 8). The fertilized egg contains three distinct bodies, the 

 germinal vesicle, the so-called nucleolus, and the sperm (Fig. i). 



The germinal vesicle is a very conspicuous spherical body, 

 mesuring about 19 IJL in diameter. Its chromatin is in the form 

 of small stellate bodies. There is also present a small but distinct 

 nucleolar-like body (Fig. I, n). Although the position of the 

 nucleus, as well as that of the nucleolus and of the sperm, is 

 very variable, yet it usually lies toward the pointed end of the cell. 



The so-called nucleolus in the eggs of polyembryonic insects 

 has given rise to a great deal of discussion as to its origin and 

 fate. Silvestri ('06, '08), who first described and named this 

 body, thought that it arose at an early stage of the oocyte from 

 the germinal vesicle, but Martin ('14) and Hegner ('14, '15) 



