It is also of great interest that azoospermia, has been observed to occur in animals. H. Fabricius tells of a stallion that mounted thirty-four mares in the space of two years in the most proper manner, without being able to impregnate them. In its copious semen not a single spermato. zoon was to be found. This observation is particularly valuable in regard to etiology. It shows that the belief, held by many, that azoospermia is brought about only by venereal processes is not quite justified. Here some other cause must have been active.
Azoospermia also, though much more mrely than aspermia, may ap pear temporarily, so that spermatozoa are only occasionally wanting. It must be regarded as a sort of physiological azoospermia, if after rapidly repeated connections the semen is not only reduced in quantity, but in stead of fully developed elements only younger and smaller spermatozoa appear, which gradually diminish in number, and finally disappear alto gether. Plonnies has shown this to be true by experiments on animals, Casper and especially Schlemmer by numerous observations both on men and animals. But with otherwise healthy individuals this condition lasts but a short time; after a period of rest and abstinence the spermatozoa which, because of their rapid elimination, consisted of newly-formed ele ments, the dimensions of which were small, again return to their former size and number. In a more pathological manner the spermatozoa may temporarily be wanting during excessive, long-continued, bodily exertion (perhaps also intense mental work ?), wasting diseases and conditions of weakneis that arise from severe, acute sufferings; the above-mentioned re- searches of Busch point to such an unfavorable effect of acute diseases. With local diseases of the genitals, also, there may be absence of sperma tozoa in the semen—with convalescence the spermatozoa again return; but if, in consequence of acute diseases, there are further changes in the genitals, the azoospermia may also become permanent and absolute. Psychical influences, however, seem to have no effect upon the production of spermatozoa.
Besides aspermatism and azoospermia, it seems that other causes of sterility exist that arise from defects in the semen. It must be mentioned here that in some cases of sterility brought about by certain local diseases, the spermatozoa are not entirely wanting, but are present in very small number, a condition which has been called oligozoospermia. It often is a transition to azoospermia, but perhaps it may also occur during recovery from that affection.
Recent researches have, however, made known to us still other condi tions of the sperma, which may possibly also enter into the etiology of sterility. For it is a remarkable fact that not infrequently the sperma tozoa are found motionless in the vagina very soon after cohabitation. It may of course be supposed in such cases that an abnormal secretion of the female genitals may exert a deleterious influence upon the sperma tozoa, but often the condition of the female genitals is not at all unfavor able to the spermatozoa, so that we might suppose that they were already dead when ejaculated into the vagina. It is possible, however, that the normally formed spermatozoa may be caused to die by passing through diseased seminal paths, and tIn.ough their diseased secretion. On the other
hand, the spermatozoa taken from the female genitals occasionally have not the proper shape and dimensions. Sometimes their shape is perfect, but they are too short and too narrow, such as are found after rapidly repeated connections, or in individuals that have scarcely passed the a.ge -of boyhood and in old men. It seems that sterility among too young and too old individuals depends not alone upon the quantity, but also upon the quality of the spermatozoa. If these young and small spermatozoa are also met with in manhood, it seems questionable whether they would be as well fitted for propagation as the older and larger ones. Sperma tozoa have also been found that were peculiarly misshapen. Of course from seminal emissions the changes of shape were not so marked as Men zel has found and pictured in spermatocele. The decomposition of the spermatozoa into their constituents also, i.e., the separation of the head from the middle part, often takes place very early. Although here again the influence of the vaginal secretion and the mechanical insults during microscopical examination might easily be the cause of these changes of shape, yet on the other hand it cannot be proved that the spermatozoa did not leave the urethra in this condition—in fact, researches by Haus mann seem to prove that these deformities may exist in the urethra. The suspicion would then arise that these changes were produced by the male not the female genitals. It would not be very far-fetched to imag ine that, in some inexplicable cases, sterility is due to such abnormalities of the elements of reproduction, not alone of the sperma, but also of the ovule. Certainly the researches in this direction will be more numerous in the future, and will give us the necessary information; at present it is merely a matter of conjecture.
As for the frequency of male sterility, it is, according to the latest re searches, greater than was ever imagined. Azoospermia, the most impor tant item, according to Kehrer's statistics, is very frequent (fourteen in forty eases). The researches of Schlemmer and Busch give similar results: the latter found among 100 cadavers 34 with many, 39 with few, and 27 without any spermatozoa. These figures, having been derived from the cadavers of patients, of course cannot furnish a general standard. With sufferers from chronic diseases the question of sterility scarcely ever arises. The relative frequency of azoospermia in acute diseases, however, is of great importance, as it is questionable whether this will disappear in case of recovery allowing the testicle to resume its normal function, or whether it will remain as an incurable defect. Azoospermia after gonor rhceal affections deserves an almost equal amount of attention. If we get further confirmation of the great frequency of sterility after these affections, which in various other ways can impair the power of repro duction, it will be necessary, in view of their frequency and of the rather careless therapy too often seen, that they be viewed and treated from the start as diseases having serious consequences.