ETIOLOGY OF STERILITY IN GENERAL.
_ If we examine more closely those functions which concern each one of the two interested individuals, we find that they in reality have but little that is not characteristic of the functions of other organs. As here, we have there to deal with activity of glandular organs which produce certain elements, which are excreted by particular excre tory ducts, then to be used for some certain purpose. As there, it is physico-chemical forces which are active in the performance of the sexual functions.
But just as little as the other glandular organs of the body can remain active when isolated, so is it possible for the generative organs to perform their task only when in vital connection with the whole body. Here as there the influence of the nervous system is a particularly important one. But as the entire body is markedly influenced by external forces, and manifests this influence in modifications of the functions of organs, so the sexual functions are in the same way interrupted by external influences.' It is the same with those disturbances of the sexual e,apabilities to which the sterility of both of those parties participating in the act of generation may be accreditol. As certain, even though often unimportailt, anatomical changes of other organs appear to modify their functions in a marked man ner, so purely local material disturbances are in a position to destroy the task of the generative organs. To positively adhere to the view that the most frequent cause of unfruitfulness is to be sought in defects and diseases of the genitals of different degrees, is, according to my opinion, perfectly justified. But to me there is no doubt but that through the nervous system and by constitutional disturbances, urgruitfulness, most markedly in males, may be occasioned. How this influence is exerted is as yet not always clear; whether the nervous influence and the general disturbance of nutrition alone are sufficient, or whether they make themselves felt by secondary disoases of the genital organs, is undoubtedly very often not to be determined, but it would be very unfair to deny this mode of origin of sterility. It is just as difficult to prove that certain factors of the external world can prevent the occurrence of conception. Whether this influence is exerted through the nervous system or through alteration of the bodily con stitution, is probably more difficult to prove. It is only weighty argu ments that compel us to allow this disturbing influence to be accountable.
According to this, the causes of sterility would have to be sought in local diseases, nervous influences and constitutional affections, and further in external influences. As undisputed as this proposition truly is, just so difficult is it on the other hand to fix the definite cause in the great ma jority of concrete cases. In no department probably of gynecology does
such mystery pertain in respect to the etiological relations as in the study of sterility. I will revert to the reasons for this uncertainty in speaking of the diagnosis.
Endeavors to clear up the causes of sterility aro not wanting; this has been attempted in many ways, One method that has been employed for this purpose is that of analogy, the comparison of similar conditions in other organisms. A great philosophic,a1 and partly also practical interest is offered to follow the sterility, as well as the disturbances of the process of procreation, beyond the human species into the plant and animal king doms.
As regards actual unfruitfulness, we do not know what the conditions are among those animals living in a wild and free natural state, nor have we any very definite knowledge derived from the observation of domesti cated animals. It is only of those animals, the horse, cattle, etc., con cerning whose regular reproduction we interest ourselves from reasons of eeonorny, that we possess any, even though very uncertain experiences. Even these are narrowed down to confirming general causes, which under el-timate fertility, or cause seeming sterility, or which retard fructescence. On the contrary, we lose countless exact observations of single cases; such sterile domesticated animals, beca,use not actually sick, are seldom brought under the observation of the veterinary surgeon. On account of the farther economical realization (fattening) they do not come under ana tomical examination. Still, recent literature points to a few interesting observations concerning the sterility of domesticated animals, which are of great value in the explanation of human sterility. 'rheoretically valu able, but practically of little worth in the question of sterility, are those changes in fertility which occur in many animals and plants, as soon as certain influences,which manifest themselves gradually or suddenly, occur. The numerous experiments made in this matter have received a marked addition and philosophical elaboration in recent times. The Darwinian theory, which relies greatly upon these data for support, has added the most of these. The transformation of sexual life does not, however, consist always in a complete suspension of the procreative capability or a decrease of the same, but not infrequently even in an increase of fertility. The latter may be manifested in two ways, by an increase of the fraits themselves or by a more frequent occurrence of the period of reproduc tion. The change produced can also only consist in au improvement or deterioration of the descendants. The factors concerned in these changes can be of different kinds.