. A text-book of comparative physiology for students and practitioners of comparative (veterinary) medicine . urroundingcells has become separated from a nest, it isknown as a Graafian follicle. while the remainder ofthe space is filled by afluid (liquor folliculi)probably either secretedby the cells themselves,or resulting from the disintegration of some of them, or both. In viewing a section of the ovary taken from a mammal atthe breeding-season, ova and Graafian follicles may be seen inall stages of development—those, as a rule, nearest the surfacebeing the least matured. The Graafian folli
. A text-book of comparative physiology for students and practitioners of comparative (veterinary) medicine . urroundingcells has become separated from a nest, it isknown as a Graafian follicle. while the remainder ofthe space is filled by afluid (liquor folliculi)probably either secretedby the cells themselves,or resulting from the disintegration of some of them, or both. In viewing a section of the ovary taken from a mammal atthe breeding-season, ova and Graafian follicles may be seen inall stages of development—those, as a rule, nearest the surfacebeing the least matured. The Graafian follicle appears to passinward, to undergo growth and development and again retiretoward the exterior, where it bursts, freeing the ovum, which isconducted to the site of its future development by appropriatemechanism to be described hereafter. Changes in the Ovum itself.—The series of transformationsthat take place in the ovum before and immediately after the REPRODUCTION. 59 access of the male element is, in the opinion of many biologists,of the highest significance, as indicating the course evolution m. i-r--^ZX? Sill Mw/M Fig. 58.—Sagittal section of the ovary of an adult bitch (after Waldeyerl. o. e, ova-rian epithelium; o. t, ovarian tubes; , younger follicles; , older follicle;d. v, discus proligerus, with the ovum; e, epithelium of a second ovum in the samefollicle: f. c, fibrous coat of the follicle; p. c, proper coat of the follicle; e. f. the follicle (membrana granulosa); , collapsed atrophied follicle;b. /.blood-vessels; c. t, cell-tubes of the parovarium divided longitudinally andtransversely; /.(/.tubular depression of the ovarian epithelium in the tissue ofthe ovary; b. e, beginning of the ovarian epithelium, close to the lower border ofthe ovary. has followed in the animal kingdom, as well as instructive inillustrating the behavior of nuclei generally. 60 COMPARATIVE PHYSIOLOGY. The germinal vesicle may acquire powers of slow movement(a
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