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Updated: May 2, 2025
The reproductive organs for the production of eggs and spermatozoa form little protuberances on the outside of the body below the tentacles. But hydra reproduces mostly by budding; new individuals growing out of the side of the old one, like branches from the trunk of a tree, but afterward breaking free and leading an independent life.
Semen may be found on the linen of the woman and man, and will be recognized under the microscope by the presence in it of spermatozoa, minute filamentary bodies with a pear-shaped head; but it must not be forgotten that the non-detection of spermatozoa is no proof of absence of sexual intercourse, for these bodies are not always present in the semen of even healthy adult young men.
This may cause a temporary sterility, but if persisted in, as is frequently the case in show animals, the sterility becomes permanent because of the genital glands failing to secrete ova and spermatozoa, or the lack of vitality of the male and female elements.
The spermatozoa must be looked upon as the fertilizing element of the semen, while the liquid portion of the semen probably contains that mysterious element which, absorbed into the body, produces virility and which, passed out with the spermatozoa, may have an important role to perform in the fertilizing function.
Spermatozoa must not be mistaken for the Trichomonas vaginæ found in the vaginæ of some women. The latter have cilia surrounding the head, which is globular. Florence's Micro-Chemical Test for Spermatic Fluid. Barberio's Test. Mix a drop of the spermatic stain with a drop of a saturated solution of picric acid, when needle-shaped yellow rhombic crystals are formed. Gonorrhoeal Stains.
It is well known how Weismann was led, by his hypothesis of the continuity of the germ-plasm, to regard the germinal cells ova and spermatozoa as almost independent of the somatic cells. Starting from this, it has been claimed, and is still claimed by many, that the hereditary transmission of an acquired character is inconceivable.
Hermaphrodite animals, as has been pointed out by Correns and Wilson, cannot be brought under this scheme at all. In the earthworms, for instance, we have, in every individual developed from a zygote, ova and spermatozoa developing in different gonads in different parts of the body. The differentiation here, therefore, must occur in some cell-division preceding the reduction divisions.
In this way, though the sexual excitement is brought quickly under abeyance, we can rest assured that a certain number of spermatozoa have been released from the testes; and that the other secretions have been increased in volume. The excitement may be sufficient even to cause an erection, and produce a few drops of the secretion of Cowper's glands.
The vesicles and prostate may be looked upon as the commissariat of the army of spermatozoa; the vesicles accumulating a stock of supplies to be drawn upon at short notice; the prostate representing a factory where a considerable quantity of supplies can be prepared at short notice.
The soma with its male and female somatic characters has nothing to do with the question, since somatic sex-differences may be altogether wanting, and moreover, the essential male character, the formation of spermatozoa, is by the Mendelian hypothesis due to descent of the male gametes from the original fertilised or unfertilised ovum.
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