. A text-book of comparative physiology for students and practitioners of comparative (veterinary) medicine. Physiology, Comparative. THE DEVELOPMENT OP THE EMBRYO ITSELF. I33 Semen itself, thougTi composed essentially of spermatozoa, is mixed with the secretions of the vas deferens, of the seminal vesicles, of Cowper's glands, and of the prostate. Chemically it is neutral or alkaline in reaction, highly albuminous, and con- tains nuclein, lecithin, cholesterin, fats, and salts. The movements of the male cell, owing to the action of the tail (cilium), suffice of themselves to convey them to th
. A text-book of comparative physiology for students and practitioners of comparative (veterinary) medicine. Physiology, Comparative. THE DEVELOPMENT OP THE EMBRYO ITSELF. I33 Semen itself, thougTi composed essentially of spermatozoa, is mixed with the secretions of the vas deferens, of the seminal vesicles, of Cowper's glands, and of the prostate. Chemically it is neutral or alkaline in reaction, highly albuminous, and con- tains nuclein, lecithin, cholesterin, fats, and salts. The movements of the male cell, owing to the action of the tail (cilium), suffice of themselves to convey them to the ovi- ducts ; but there is little doubt that during or after sexual con- gress there is in the female, even in the human subject, at least. Fig- 138 —Uterus and ovaries of the sow, semi-diagrammatic (after Dalton). 0, ovary: H, Fallopian tube; h, horn of the uterus; of the uterus; v, vagina. in many cases, a retrograde peristalsis of the uterus and ovi- ducts which would tend to overcome the results of the activity of the ciliated cells lining the oviduct. It is known that the male cell can survive in the female organs of generation for several days, a fact not diiBcult to understand, from the method of nutrition of the female cell (ovum) ; for we may suppose that both elements are not a little alike, as they are both slightly modified amoeboid organisms. Nervous Mechanism —Incidental reference has been made to the directing influence of the nervous system over the events of reproduction; especially their subordination one to another to bring about the general result. These may now be consid- ered in greater detail. Most of the processes in which the nervous system takes part are of the nature of reflexes, or the result of the automa- ticity (independent action) of the nerve-centers, increased by some afferent (ingoing) impressions along a nerve-path. It is not always possible to estimate the exact share each factor takes, which must be highly variable. Certain exp
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