leave the penis, the venous cavities in it fill up with venous blood until the whole is rigid. When rigid this organ is able to penetrate the female entrance, and there the further stimulation of contact calls out the sperms from their storehouses, the seminal vesicles, and they pass down the channel (the urethra) and are expelled. If this is clear, it will be realised that the stiffening and erection does not _necessarily_ call for relief in the ejaculation of sperm. If the veins can empty themselves, as they naturally do when the nervous excitement which restricted them locally passes, the erection will subside without any loss of sperms, by the mere passing back of the locally excessive blood into the ordinary circulatory system. This can happen quite naturally and healthily when the nerves are soothed, either physically or as a result of a sense of mental peace and exaltation. When, on the other hand, the local excitement culminates in the calling up and expulsion of the sperms, after it has once started the ejaculation becomes quite involuntary and the sperms and the secretions associated with them pass out of the system and are entirely lost. Of what does this loss consist? It is estimated that there are somewhere between two and five hundred million sperms in a single average ejaculation.[5] Each single one of these (in healthy men) is capable of fertilising a woman's egg-cell and giving rise to a new human being. (Thus by a single ejaculation one man might fertilise nearly all the marriageable women in the world!) Each single one of those minute sperms carries countless hereditary traits, and each consists very largely of nuclear plasm--the most highly-specialised and richest substance in our bodies. It is not surprising, therefore, to find that the analysis of the chemical nature of the ejaculated fluid reveals among other things a remarkably high percentage of calcium and phosphoric acid--both precious substances in our organisation. [5] See Pflügers Archiv., 1891. It is therefore the greatest mistake to imagine that the semen is something to be got rid of _frequently_--all the vital energy and the precious chemical substances which go to its composition can be better utilised by being transformed into other creative work on most days of the month. And so mystic and wonderful are the chemical transformations going on in our bodies that the brain can often set this alchemy in motion, particularly if the brain is helped by _knowledge_. A strong will can often calm the nerves which regulate the blood supply, and order the distended veins of the penis to retract and subside without wasting the semen in an ejaculation.