40 KINGSLEY. [Vol. VII. 



Ovigenesis. 



I have made no extended observations upon the origin and 

 development of either eggs or spermatozoa. The gross struc- 

 ture of the ovaries has been described by van der Hoeven ('38), 

 Gegenbaur ('58), and Owen ('72), while Gegenbaur adds a, short 

 account of the origin of the ^g^, presented in abstract by Lud- 

 wig ('75). Owen gives a line or two to the testis, while Benham 

 ('83) describes it more in detail. Packard ('72) figured the sper- 

 matozoa, Lankester ('78) noted the fact that they are motile, and 

 Packard ('80) refers to the histology of the testis and speaks 

 briefly of the development of the ovary. Aside from these and 

 one or two older papers, at present inaccessible to me, I 

 know of no published results upon the reproductive organs of 

 Limulus. 



In a female Limulus four inches long (not including the cau- 

 dal spine) I find the ovarian caeca lined with columnar epithelium 

 which secretes a delicate cuticle, and outside of this epithelium a 

 connective tissue tunica propria. As in other higher Metazoa, 

 this epithelium is the ovogenetic layer, certain of its cells becom- 

 ing modified into primordial ova. These at first lie within and 

 form a part of the parent epithelium, but with growth the eggs 

 pass to the outside of the epithelium and, separating the tunica 

 from the other layer, come to lie between the two. (Figs, i 

 and 2.) 



The primordial ova are distinguishable not only by their size, 

 but by their more deeply staining cytoplasm, in which the yolk 

 spherules, so characteristic of the mature eggs, are lacking, unless 

 the minute granules are to be regarded as such. Around the 

 cytoplasm of the older eggs, after leaving the epithelium, there is 

 a delicate membrane, the origin of which I have not been able to 

 decide, but I think it a true vitelline membrane. The nuclei of the 

 ovarian eggs vary considerably with age. In the younger ones 

 they are strongly staining bodies of about the size of the nucleoli 

 of older eggs. In these no reticulum is visible. A little later this 

 nucleus is surrounded by a clear space which separates it from 

 the darker and more granular cytoplasm. This clear space shows 

 processes radiating into the surrounding substance. In still 

 older eggs a well-marked nuclear membrane is distinguishable, 

 inside of which is a faintly staining chromatin (.'') reticulum 



