194 PROCEEDINGS OF THE NATIONAL MUSEUM. vol.39.; 



THE EGG PREVIOUS TO DEVELOPMENT. 



FORMATION OP THE EGG. 



Claus (1862) was the first to call attention to the long threads or I 

 filaments which are connected with the older oocytes inside the ovary! 

 of Achtheres. Beneden (1870) found the same condition in Anchor-\ 

 ella and Lernseopoda, while Kerschner (1879) and Giesbrecht (1882)' 

 discovered it in Congericola, Doropygus, and Notopterophorus. Thei 

 same filaments are found in connection with the eggs of Achtheres 

 amUoplitis. On being magnified (fig. 1) these filaments are seen to bej 

 composed of cells, usually discoidal in shape and packed with theiri 

 flat surfaces together like rows of coins. A cross section of a uterinei 

 process in which the eggs are partly matured shows one of these fila-i 

 ments attached to each egg and packed more or less closely against thei 

 surface of the latter. Owing to the crowding of the eggs in these uter- 

 ine processes, the threads or filaments are often coiled into a sort of | 

 ball, as seen at h in fig. 1. It will be noticed that the cells at one endj 

 of the filament are greatly reduced in size, and Korschelt and Heideri 

 suggest that the formation of new cell material possibly takes place 

 here. At the opposite end of the thread is the oocyte itself, abruptly 

 and enormously (compared with the cell filament) swollen in size. 



This increase in size is due wholly to the absorption of food mate- 

 rial or yolk globules by the oocyte, the difference in composition 

 being clearly brought out by staining. 



The entire substance of the cell filament takes a deep blue color 

 in hsematoxylin, while the oocyte, except the nucleus, takes none 

 whatever, but stains a deep red in eosin. 



According to Giesbrecht, the rows of cells loosen themselves from 

 the epithelium of the ovary in order to connect with the oocytes. 

 But whatever their origin, it is certain that they are no longer con- 

 nected with any part of the ovary in the present species, and have 

 been pushed far out into the uterine processes. As soon as the 

 terminal cell has become fully developed into the oocyte it sepa- 

 rates from the cell filament, and the cell, which then becomes ter- 

 minal in the filament, develops in its turn. And thus the process 

 continues until all the cells in the filament have been successively 

 formed into eggs. 



As Beneden pointed out, the difference in egg development be- 

 tween this family of LernseopodidoB and the Caligidse lies in the fact 

 that the latter possess but a single ovarian filament, in which a 

 series of cells develops simultaneously. 



Here in Achtheres (the Lernseopodidse), on the contrary, there are 

 many of these ovarian cell filaments, and in each of them the ter- 

 minal cells develop successively, one after the other. A similar 



