SELECTED NOTES. 387 



ance of the seminal sac with its contents. The cellular structure 

 previously referred to now occupies the whole of the exhausted 

 spermatophore, as may be seen in Fig. 7, an irregular line only 

 serving to mark where the surrounding cellular structure has 

 pressed in to fill up the void. It is plain that it is by the expan- 

 sion of this tissue that the spermatic fluid is gradually expelled. 

 Whether this expansion is a vital process, the cells multiplying and 

 so pressing out the sac and its contents, or whether the cells, 

 originally minute and occupying little space, gradually absorb 

 water through the cuticle and so produce the same effect, I am 

 unable to say. The spermatic fluid, of course, retains its vitality ; 

 may not the surrounding cellular tissue do the same until its 

 purpose is served ? 



At ov.^ Fig. r, is seen a cellular mass, which on expulsion from 

 the body when the animal is crushed assumes the appearance seen 

 in Fig. 12, and consists of large nucleated cells. At /, in Fig. 2, 

 is a delicate sac occupying the same position, and filled with 

 minute cells, as shown in Fig. 13. The anterior extremity pre- 

 sents a brownish granular appearance From the manifest dis- 

 similarity of these organs in the male and female, there can be no 

 doubt that they are respectively the ovary and testis; the nucleated 

 cells in the female being the ova with the germinal vesicle and the 

 minute cells in the male being spermatic cells, within which the 

 spermatozoa are formed. 



In the brownish granular appearance in the anterior portion of 

 the testis I think I recognise the source of the similar granules 

 found subsequently at the extremity of the spermatophores. The 

 ovary and testis thus described appear to be single organs, occu- 

 pying a mesial position in the body, but doubtless they are really 

 paired organs, which is, I think, the universal rule. We have seen 

 how a pair of closely appHed organs may be taken for one in the 

 eye of Daphnia. The ova here originating undergo subsequent 

 development in two lateral masses — one on either side. Here the 

 granular yelk is formed and the ova take the dark shade seen in 

 Fig. I. Ultimately, they are passed into a receptacle attached to 

 the base of the abdomen, as seen in Figs, i and 5, and after being 

 carried about for some time finally fall off, their further history 

 being to me (at least) unknown. 



