. The cyclopædia of anatomy and physiology. Anatomy; Physiology; Zoology. [112] OVUM. Fig. 77*.. Oeum and Slicropyle of Dipterous Insects. (From Leuckart.) A. Ovum of Melophagus ovinus (Muscida). 1. The entire ovum, presenting at its upper part the adherent mass of spermatozoa close to the micro- pyle. 2. This upper part more highly magnified, showing a section of the micropyle, above which the point of the conical mass of spermatozoa glued together by an albuminous substance is inserted, •while externally the filaments float free. 3. The micropyle apertures seen directly from above. B. Side v
. The cyclopædia of anatomy and physiology. Anatomy; Physiology; Zoology. [112] OVUM. Fig. 77*.. Oeum and Slicropyle of Dipterous Insects. (From Leuckart.) A. Ovum of Melophagus ovinus (Muscida). 1. The entire ovum, presenting at its upper part the adherent mass of spermatozoa close to the micro- pyle. 2. This upper part more highly magnified, showing a section of the micropyle, above which the point of the conical mass of spermatozoa glued together by an albuminous substance is inserted, •while externally the filaments float free. 3. The micropyle apertures seen directly from above. B. Side view of the upper part of the ovum of another insect of the same order, showing a single micropyle aperture and the dotted structure of the chorion. small mass, formed of the spermatozoa which have met with the ovum in its descent through the female passage, comes to be lodged in the depression of the micropyle, and is fixed in that situation by a lid or covering of albu- minous matter. It is somewhat remarkable that the greater part of this mass remains for a long time apparently without any change, even when embryonic development has ad- vanced to a considerable extent; but he as- certained that a few of the spermatozoa be- longing to the mass, usually not more than three or four, really enter the ovum and effect the change of fecundation. We are, however, as yet at a loss to conjecture what farther purpose may be served by the mass of per- sistent spermatozoa near the micropyle. Leuckart has also made the novel and interesting observation, that the depression and aperture of the micropyle become at a later period converted into a deeper funnel, which is connected directly with the mouth of the embryo, and undoubtedly serves, ac- cording to this author, to convey nourishment from without to the embryo. The head of the embryo lies, according to Leuckart and other observers*, in all instances, at that end or pole of the ovum which is uppermost in the oviduct, as may be most e
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