Equally important are the results that relate to the accessory organs of reproduction, such as the glands that open into the vas deferens (prostate, Cowper’s gland, etc.) and the copulatory organs also. In the castrated mammals these organs diminish in size. On the other hand, after destruction of the germ-cells in the testes (or even when they fail to develop as in cryptorchid individuals) these accessory parts are unaffected. In birds, as will be shown, the situation is entirely different.
CYCLICAL CHANGES IN THE INTERSTITIAL CELLS IN HIBERNATING MAMMALS.
The changes that take place in the interstitial cells in mammals that hibernate and in which there is a definite rutting season following hibernation have been examined by several workers. The mole has been studied by Regaud (1904), Lécaillon (1909), Tandler and Grosz (1911); the marmot by Hauseman (1895) and Gaugini (1903); the hedgehog by Marshall (1911); and the woodchuck by Rasmussan (1917). In the mole the interstitial cells are most abundant when the tubules in which the spermatogenesis is taking place are least developed, and vice versa. In the hedgehog the increase in both tissues takes place at the same time. In the woodchuck both tissues increase rapidly after hibernation (during March and April), after which the spermatogenesis continues actively for the two following months (May and June), while the interstitial cells retrograde rapidly during April and remain at a low level for the rest of the year. Retrogression in the germinal epithelium begins in July, after the rutting season is past. It appears from this evidence that the activity of the two tissues does not always run the same course. Since the secondary sexual characters of the male, which are not well developed in these animals, are not so far as known affected by the condition of the testes, the evidence does not have any very direct bearing on our present topic. How far the sexual behavior of these mammals is determined by the quantity or by the activity of the interstitial cells is not very clear from the evidence, although there is a very noticeable increase in the amount of this tissue just before and during the rutting season. In the mole also the interstitial cells begin to increase just before the mating season, and the increase continues for several months after mating has taken place. It is difficult to judge how great or how little the change amounts to unless the whole organ is considered, for the relative volumes of the seminal tubes and the interstitial tissues does not give a measure of the total volume of these tissues, since the testes may decrease greatly in size when the seminal tubes retrograde, and the apparent increase of the interstitial cells at the time may not increase the total amount of that tissue present.
Probably more important than the ratio of interstitial tissue to tubules is the activity of the former. Rasmussan states that in the woodchuck the interstitial cells not only increase in number immediately after hibernation, but the increase in amount of this tissue is largely due to increase in the cytoplasm, in which there appears an accumulation of fatty globules in the more peripheral parts of the cells. In the central cytoplasm an abundance of fine lipoid granules develops.
Marshall has made some interesting experiments on the hedgehog at different seasons. Castration in March prior to the breeding-season has an influence on the accessory generative organs (vesiculæ seminales, prostates, and Cowper’s glands). They remain in the same undeveloped stage in which they were at the time of operation. If castration is carried out very early in the breeding-season, when the accessory reproductive organs are about half developed, their further enlargement is prevented. In so far as the accessory organs rank as secondary sexual organs, their complete development is thus shown to depend on the testes. Transection of the vasa deferentia before the beginning of the breeding-season affects somewhat the enlargement of the testes, but produces no effect on the accessory organs.
HERMAPHRODITISM IN POULTRY AND THE SECONDARY SEXUAL CHARACTERS.
Several hermaphrodite birds have been described (Brandt, 1889; Shattock and Seligman, 1906; Pearl and Curtis, 1909; Smith and Thomas, 1913; Bond, 1914; etc.). The most recent and complete account of such birds is that by Boring and Pearl. They examined in all 8 hermaphrodites, or at least 8 birds that showed in their plumage, or other secondary sexual characters, peculiarities of both sexes. Five of the birds came from Herr Houwink in Meppel, Holland, who had a stock in which there appeared, in 1911, two hermaphrodites out of 80 birds, and in 1912, three out of 80 birds. These were the birds studied by Boring and Pearl. In addition, when Pearl saw Herr Houwink’s birds in 1910, “there were then on hand a considerable number of these supposed hermaphrodite birds.” An anatomical study of the Holland birds showed that one of them was nearly a normal female; three, the authors say, were “evidently undeveloped females. They have infantile oviducts and embryonic ovaries.” It should be added that there was a tumor more than twice the size of the ovary attached to or part of the ovary. If the ovary itself was affected by the tumor, or the tumor was a part of the ovary, the slightly unusual condition of the birds might be accounted for. Of the other 3 birds, 2 are also suspected to have ovarian tumors, while in the third bird streaks of a secretion which resembles the substance of the tumor of the other two were found. The change towards male plumage in these 5 birds is probably due either to the incomplete development of ovary or to the effect of the tumor on the ovary. Although luteal cells are described as present, it seems probable that their total number might be less than in a normal bird, and hence their insufficient secretion would fail to suppress the development of male plumage. From this point of view these birds are no more hermaphrodites than is a hen with her ovary taken out.
The remaining Holland birds were entirely different. On the left side there was an ovary in an inactive condition; on the right side there was a testis, producing spermatozoa. Sections of the testis show that it is normal, consisting of a mass of tubules with very little connective tissue between them. In both ovary and testis there are “a few nests of luteal cells near the surface. The ovary contains eggs, but is abnormal to some extent.” The authors state:
“In external appearance it is more like a male than the others, which fact correlates well with the active condition of the testis and inactive diseased ovary, with only one corpus luteum scar. The interstitial cells can scarcely be held accountable for the male secondary sex characters, as the only ones in an active secreting condition are a few in the ovary.”
It is not quite clear what is meant in this quotation by the statement that the interstitial cells can scarcely be held accountable for the male secondary characters unless to suggest that they cause the development of these characters in the male, as they are supposed to do in mammals—a view that the authors do not seem at other times to hold.