7 io THE GENERATIVE ORGANS. 



chamber could enter into the formation of the eggs, so that, 

 although authors still speak of the terminal chamber as the 

 germ chamber, it is evident that, as Lubbock maintained, these 

 cells become yelk-cells if the ova in the terminal portion of the 

 oviduct ever become mature. 



Balfour [43], the most learned embryologist of his day, in 

 1881 wrote : ' The following points need elucidation with 

 regard to the ova of Insects : 



' (i) The relation of the germogen to the vitellogen, and (2) 

 the relation of the yelk to the germ.' It is evident, therefore, 

 that he was dissatisfied with the explanation given in the 

 voluminous literature of the subject, and regarded the ques- 

 tions at issue as unsettled, and I am not aware of any investi- 

 gations which have been made since then, with the exception 

 of my own, which tend to throw any further light on the 

 subject. 



The remarkable corpuscles first found imbedded in the 

 epithelium of the parovaria by myself, in 1888, are so 

 strikingly like the germ ova of other animals that I have no 

 hesitation in regarding it as the germ-gland, just as I have no 

 hesitation in regarding the great ovaries as yelk-glands. 



The question as to how these germ ova reach the yelk and 

 enter the egg is a subsidiary one, but one which it is not 

 difficult to answer, although it is by no means easy to find 

 direct proof of the truth of the answer. 



As the eggs pass down the oviduct, each remains for a brief 

 space in the sacculus, with its micropyle closely related to the 

 orifices of the ducts of the parovaria. It is therefore quite 

 possible for a germ ovum to enter it by the micropyle. The 

 egg next passes into the uterus, and rests with its micropyle in 

 immediate relation with the ducts of the spermathecai, from 

 which no one doubts the sperm-cells enter the egg. 



It may be objected by some that developing ova are frequently 

 found in the oviducts ; but it must be remembered that such 

 eggs must have been impregnated, and therefore have evidently 

 been in the uterus, hence they must have passed the orifices of 

 the ducts of the parovaria in their descent ; and the fact that 



