FORMERLY, it was usually thought that the study of the sexual life had been completed when reproduction had been correctly explained. That is not so. Reproduction is only one of the phenomena of sexual life, fertilisation is once and for all an exceptional case, and can affect even in the most favourable circumstances only one or two, or at most five, the countless sperm-cells. The stimulus of sexual pleasure in which all sperm-cells take such an active part is for every adult individual, day and night, a burning question, one of the chief factors of our life-energy. It will be the task of this work to discuss sexual life in this respect and to determine its chain of causality in all its details, so that we shall in future be able consciously to control this impulse better than at present.
In the previous chapters we have considered sexual life primarily as a tissue-formation; from now on it will appear more in its secretory aspect. In the next chapter we shall first discuss the anatomy of the excretory duct-system. In order to understand this better, we shall first make a few remarks concerning the abdominal cavity as a container of the excretory organs.
The abdominal cavity contains the three large excretory organs, the bladder in front, the rectum behind, and the genital canal in the middle. The latter, however, differs in the two sexes. In the female the whole genital canal, in the male only its middle portion, including the two seminal vesicles, occupies this portion. The be-ginning and the end of the male genital canal have migrated from the abdominal cavity, the testicles have passed outwards through the anterior wall and the urethra has pierced the lower wall.
These three excretory systems are evacuated towards the exterior by means of peristaltic (progressive) contractions of their membranous muscular walls. These muscular contractions in the interior of our bodies are imperceptible to us and therefore enter little into our consciousness. Our consciousness would therefore exert but little control over these three excretory functions, if the three organs were not contained in a common abdominal cavity with movable walls, as in a sack. Only the orifices in its lower wall remain open.
These movable walls consist of red muscle-fibres, which, since they can be directly observed on the body surface, are certainly under the command of our consciousness. They are the abdominal muscles which stretch from the ribs to the edge of the pelvis. When these abdominal muscles are contracted and the abdominal cavity is thereby energetically compressed, contraction will easily be caused in the three internal organs by the increased pressure. This action can, however, only be an indirect one, since the proper evacuative action of the said organs is peristaltic.
But how about the lower end where the floor of the pelvis has to be closed? The gluteal muscles are unable to close it since they are attached only to the exterior of the pelvis where they serve to extend the thigh. They overlap everything while we are standing erect. When we are sitting or crouching, however, that is, when they are not contracted, they lie lateral to the two ischial tuberosities, so that the lower pointed end of the pelvis becomes exposed. Thus four fixed points are easily palpable exteriorly, the ischis laterally, the coccyx posteriorly and the lower margin of the os pubis anteriorly. Here there is an acute angle in which the urethra may be felt as it bends upwards at this point. The small space between these four fixed points is the floor of the pelvis, and is completely filled by a special muscular layer, the perineal musculature. We must attach the greatest importance to this small group of muscles as the endings of the three excretory organs pass right through it.
This muscular layer does not lie in one plane but arches downwards in the same way as the diaphragm arches upwards. Corresponding to the sack-like form of the abdominal cavity this muscular layer is slightly lower in the middle. The two ischia laterally are somewhat lower than the coccyx at the back, and considerably lower than the pubic bone in front. It is this latter inclination of the floor of the pelvis which causes the upward direction of the penis during erection.
The floor of the abdomen like all other abdominal muscles consists of red muscle tissue and can contract reflexly as well as voluntarily, very readily. Since, however, the mutual mobility of the three pelvic bones to which they are joined has been reduced to zero in the adult, these muscles can no longer be used for movement of the skeleton. They only serve, when necessary, effectively to close the three tubes, like three lock-gates.
In order to reach the exterior these ducts have to pass right through this muscular layer. We may say more correctly, perhaps, that the various muscle-fibres become deposited between the canals. If such a canal is half surrounded on either side, the end result is almost as satisfactory as if it had been surrounded by a proper sphincter muscle. When they contract, these muscles can greatly interfere with the free outlet of the ducts and may even close them completely, especially if they are employed simultaneously and the whole of the perineal region is thereby raised.
Every adult knows that the internal involuntary sphincter of the bladder is nearly always adequate to prevent the urine escaping. Only when it is in danger of being overpowered do we, in our apprehension, contract the external voluntary closing muscles.
The same holds good in the passing of faeces. One of my patients once had the external closing muscles completely torn owing to an extremely ;difficult labour. She, however, refused to have an operation to repair it until all possibility of giving birth to children had passed, as otherwise labour would each time be as difficult as before. This lady has, however, suffered no inconvenience through it except in cases of threatening diarrhoea.