226 BUMPUS. [Vol. V. 



the outer portion of the egg-cell. The yolk spheres lying imme- 

 diately under the vitelline membrane are considerably smaller 

 than those lying deeper. They are embedded in a clear sub- 

 stance, which is soon found to form a distinct peripheral cov- 

 ering. 



The Mature Ovarian Egg. 



As has been already noted, eggs which I consider to be ma- 

 ture were found lying free in the ripened ovary. These, though 

 only enclosed by the primary egg-membrane, closely resembled 

 young external eggs ; and many, when viewed with a low-power 

 lens, show most clearly that they are made up of two unequal 

 or subequal masses. The smaller of these often appears as a 

 cap, separated from the larger by a distinct groove (PI. XIV, 

 Fig. A). In certain eggs, however, the smaller portion seems 

 to be submerged in the larger, which almost encloses it. This 

 double structure may occasionally be found in eggs that have 

 been but a short time extruded. Such eggs do not develop as 

 do their fellows. I conclude that outside the ovary the retention 

 of the double structure is abnormal. 



A second feature of the adult ovarian egg, and one that may 

 also be observed in eggs immediately after oviposition, is the 

 gathering of a clearer layer, quite devoid of yolk matter, at one 

 pole, as shown on PI. XIV, Fig. B. No definite relation in posi- 

 tion, or otherwise, seems to be borne by this clear layer to the 

 accessory cap-shaped portion described above. Several eggs 

 which I have examined show the two at varying positions, 

 sometimes associated, sometimes quite apart. 



A cross-section of an egg at this stage is given on PI. XVI, 

 Fig. i. The nucleus, not materially changed, is seen to occupy 

 a central position. Nor is the perinuclear halo materially differ- 

 ent from that shown in Fig. n. The yolk is finely granular, 

 that of the accessory yolk-bearing portion being not essentially 

 different from the rest, though a central mass of protoplasm is 

 to be seen in certain examples. The line of demarcation, more- 

 over, between the larger and smaller portions is clearly shown. 

 My conclusion is that we have here simply a case of fusion of 

 two egg-cells. 



A reference to the above-mentioned figure will show the pres- 

 ence of chromatin granules, elements of the plasma vacuoles. 



