Mr. H. J, Carter on Microscopic Filaridse. 115 



Fig, 17. Nuclear points and daughter cells in a more advanced state^ 

 showing that there are spermatic cells of different sizes, and with 

 a variable number of nuclear points in them. 



Fig. 18. Ditto, ditto, in a still more advanced state, where the daughter 

 cells surrounding the nuclear points have become apparent. The 

 last three figures illustrate the granular state of the cells seen at 

 h, fig. 1.3. 



Fig. 19. Spermatic cells of different sizes, after the spermatozoa have be- 

 come nearly developed and nothing but a few fragments of the 

 endoplasm remain : a, spermatic cell containing only one daugh- 

 ter cell, and therefore yielding only one spermatozoon (had there 

 been no cell round the spermatozoon, then this cell must have 

 been taken for a daughter cell) ; 6, ditto containing two daughter 

 cells ; c, containing four ; d, containing twelve, and e, upwards of 

 twenty. Each spermatozoon must have been surrounded by a 

 daughter cell ; but as these were only seen in a and h, they are 

 only inserted there, it being my object here particularly to repre- 

 sent the figures of this series as they appeared to me. /,/,/, un- 

 employed or refuse fragments of the endoplasm — that is, those 

 parts which have not gone to the nourishment of the daughter 

 cells ; and the like is seen in the daughter cells themselves, being 

 the residue of their contents which have not entered into the 

 formation of the spermatozoa; g shows a peripheral arrangement 

 of the elongated nuclei and, of course, the daughter cells, though 

 the latter did not come into view here. It is this peripheral 

 arrangement which I cannot reconcile with the radiated one, but 

 which I am inclined to think may arise from dislocation of the 

 group of cells during their forcible expulsion. 



Fig. 20. Group of daughter cells with their contained spermatozoa ar- 

 ranged in the radiated form (seen at c, fig. 14), but here without 

 the parent cell : a, group of eight, arranged in a radiated form 

 here, within the parent cell. 



Fig. 21. Spermatic cells with the daughter cells and their contained sper- 

 matozoa leaving them : a, b, ditto, showing the way in which the 

 parent cell is pushed before the daughter cell into a conical form ; 

 c, daughter cells still adhering to the parent cell. Fig. 14 h and 

 fig. 13 k show the state of the daughter cells containing the 

 spermatozoa after they have left the parent cells, as they fill the 

 large end of the testicular sac and dilatations of the oviduct re- 

 spectively. 



Fig. 22. Spermatozoa struggling to get out of their cells, illustrative of 

 those in the upper part of the oviduct especially, and also of many 

 in the large end of the testicular sac. See also here the unem- 

 ployed fragment of endoplasm to which I have already alluded. 



Fig. 23. Daughter cells, illustrative of the development of the spermato- 

 zoon, in which the latter is seen to be formed from the nuclear 

 point, which further appears to pass into the head first, as it be- 

 comes elongated : a, daughter cell containing endoplasm and 

 nuclear point ; b, nucleus elongated ; c, nucleus transformed into 

 spermatozoon, and all the endoplasm, with the exception of the 

 fragment already mentioned, absorbed (direct view) ; d, lateral 

 view of ditto. The tail is too minute and transparent here to be 

 seen ; but in the cells of the foregoing group, though still invisi- 

 ble, its effect upon the form of the daughter cell is obvious. 



Fig. 24. Spermatozoon of Urolabes palustris, normal form, 1 -600th of an 

 inch long, 



8* 



