58 J, T. CUNNINGHAM. 



the germinal epithelium or produced otherwise; the former 

 method is that believed to obtain by the best authorities in all 

 Vertebrates, and I have no evidence against its occurrence in 

 Myxine. As the eggs grow larger by the accumulation of yolk 

 they pass inwards towards the attached border of the mesoarium^ 

 the largest and oldest being always the most internal. These 

 large eggs appear when a specimen is first opened to hang from 

 the edge of the ovary, but examination of the organ in liquid 

 shows at once their true relations. The mesoarium is con- 

 tinuous with the connective-tissue sheath of the follicle in the 

 largest ovarian egg, as well as in the small ones, along a line 

 which passes round the longest circumference of the ellipsoid 

 formed by the follicle, and the transition between the two 

 structures is abrupt ; the mesoarium in the immediate neigh- 

 bourhood of its attachment to the follicle is as thin as else- 

 where and is easily torn, so that the larger eggs are easily 

 separated, follicle and all, from the ovary when the animal is 

 roughly handled. The weight of the large egg causes the 

 mesoarium to be stretched, and each egg hangs down beyond 

 the edge of the ovary, seeming at first sight to be enclosed in a 

 bag formed by part of the mesoarium. But the relation of the 

 two is always as I have described above ; and it does not differ 

 from the relation between egg follicle and ovarian stroma in 

 Elasmobranchs and other Vertebrates except in the contrast in 

 thickness between the ovarian egg and the surrounding portion 

 of the ovary. In order to ascertain the structure of the fol- 

 licle and egg membranes I cut series of sections through the 

 polar portions of the largest ovarian eggs I could find. Fig. 2 

 represents the appearance of one of these sections passing 

 exactly through the pole of the egg. The egg from which the 

 section was taken was 16 mm. in length, and neither by external 

 examination nor from the sections could any trace of the polar 

 threads be discovered. In the section the thickest and most 

 external layer is the connective-tissue capsule (a), composed of 

 very thin interlaced fibrils with numerous small nuclei. This 

 layer is disposed in laminae parallel to the surface of the follicle, 

 and in it are numerous small elongated spaces, some of which 



