328 DAVENPORT ACADEMY OF NATURAL SCIENCES. 



In its earliest'stage the ovi-^apsule appears as a simple cell less than 

 2i fi in diameter imbedded in tiie tissue in' the anterior portion of the 

 ovary. It gradually increases in size, and is pushed farther and farther 

 back by the continued development of new cells, until finally it becomes 

 comparatively free within the ovary (or oviduct) except that it remains 

 attached by a pedicle at one end (figs. 6 and 7). It is now y,0 ^ to 40 /^ in 

 diameter and appears to consist of a number or clear cells or globules 

 Imbedded in a clear homogeneous substance, and the 'Whole inclosed in 

 a thin clear membrane. Tliis membrane seems to form a part of, or at 

 least to be derived from, the tissue in which the capsule was originally 

 imbedded, though it is not impossible that it may be a continuation of 

 the membrane of the ovary itself. 



A little later (fig. 8) the ovicapsule has increased considerably in size, 

 and can now be plainly seen to contain three or four rather large clear 

 apparently nucleated cells, (vitelligenous cells) always situated in the 

 free end, and one cell filled with a granular matter always found nearer 

 the attached end of the capsule. This granulated cell grows rapidly and 

 evejitually forms the ovum or egg, and its granular contents becomes 

 the vitellus or yolk. It is sometimes seen to be attached by a slender 

 filament to a small group of granules, situated between the vitel- 

 ligenous cells. When a little further progressed (fig. 9) the ovum is 

 easily seen to be surrounded by a rather thick layer of large oval epith- 

 elial cells. Tliis epitlielial layer undoubtedly extends around the vitel- 

 ligenous cells also, but being there much thinner it is less apparent. 

 The ovum now becomes elongated and of a distinct oval form, (fig. 10) 

 causing a corresponding change in the shape of the capsule. As it con 

 tinues to grow m size the different parts become better defined. The 

 capsule becomes slightly constricted just behind the vitelligenous cells 

 forming a 'head'' which is at first distinctly broader than the "body," 

 as that part containing the ovum may be designated. (Fig. 10 ; re, vitel- 

 ligenous cells ; g, gathering of granules connected with the ovum by a 

 filament ; oc, membrane of the ovicapsule ; y, vitellous or yolk ; c/i, vitel- 

 line membrane ; cp, layer of epithelial cells.) 



The ovum continues to grow very rapidly, while the vitelligenous cells 

 increase in size more slowly, so that the "body" of the capsule soon be- 

 comes distinctly broader than the " head." The vitellus is now (fig. 12) 

 seen to be composed of vitelline or yolk globules of very variable size, 

 some of them being very large. The cells of the epithelial layer are 

 very distinct, and are seen to contain some fine granular matter. [In 

 Borne diseased specimens which I examined the ovum was abortive, 

 while the epithelial cells were abnormally developed, and the granules 

 which they contained were seen to have a distinct vibratory movement.] 



The vitelligenous cells now gradually cease to increase in size, while 

 the ovum continues to grow rapidly and the yolk globules become grad- 

 ually more uniform in size and appearance. The epithelial cells begin 

 to show indications of disintegration, and finally cease to exist as such. 

 (Although there are three or four of the large vitelligenous cells it often 



