36 Mr. H. J. Carter on Microscopic Filandse. 



mass of minute nucleated vesicles or cells occupying the pointed 

 extremity of the ovisac, to which we have given the name of 

 "ovary," and, gradually becoming larger with their distance 

 from this point, at last come to occupy respectively an entire 

 transverse portion of the tube, so as to form a single file of ova, 

 which, divided by transverse straight lines, arising from the 

 parallel approximation of their coats, thus cut the ovisac into 

 graduated divisions, which increase in width as they approach 

 the fallopian tube, where they end (c), the remaining csecal por- 

 tion being filled with the granular matter already mentioned, to 

 which we shall direct our attention more particularly hereafter. 

 Up to this point, the germinal vesicle and its nucleus, together 

 with the yelk, are observed to be gradually increased in size, 

 but not surrounded by more than one membrane, which is deli- 

 cate, soft, and easily ruptured. The ovum now passes into the 

 fallopian tube, which is filled with spermatophorous cells, each 

 of which, as before stated, bears a single spermatozoon ; and, as 

 it traverses these, the germinal vesicle and its nucleus gradually 

 disappear, and a second membrane, viz. the coriaceous coat, is 

 added (/), when the ovum assumes an elliptical shape, and, 

 arriving at the vagina, is laid before segmentation commences. 



Development of the Spermatozoon (fig. 14). The spermatozoa 

 are developed from minute nucleated cells which fill the small 

 ends of the testicular sacs (a), which are in fact the testes, each 

 of which cells consists of a cell- wall lined by a portion of proto- 

 plasm, in one pai't of which is the nucleus (fig. 15). The cell 

 now increases in size, and a number of points or nuclei make 

 their appearance in the endoplasm, thus giving it a granular ap- 

 pearance (16). These points or nuclei now enlarge, and each pre- 

 sents around itself a cell ; during this process the whole mass has 

 much increased in size, and the original nucleus may be assumed 

 to perish (18). The endoplasm now gradually disappears, while 

 the points or nuclei enclosed within their proper cells become 

 larger and elongated, till at last nothing but a few fragments of 

 the endoplasm remain, and the spermatophorous cells, which are 

 indeed the daughter cells, are observed to be adherent to the 

 inner periphery of the parent cell (19). At length the elon- 

 gated nuclei with their cells force themselves through the parent 

 cell, and, after remaining pendent to it for a short time, finally 

 obtain their liberation, when the elongated nucleus of each cell 

 is seen to be a spermatozoid (21). The spermatophorous cells 

 thus liberated fill the large ends of the testicular sacs (14 d), 

 and passing in this state into the seminal duct, are at length 

 transferred from the male to the female, where, as before stated, 

 they fill the dilated portions of the oviduct or fallopian tube 

 (13 g, k). They are now observed to consist of a delicate, thin, 



