794: GENERATION. 



penetration of the male organ is not essential, and that fecundation may 

 occur provided the seminal fluid find its way into even the lower part of the 

 vagina. Conception has also followed intercourse when the female has been 

 insensible or entirely passive. Unlike certain of the lower animals, the human 

 subject presents no distinct periodicity in the development of the spermato- 

 zoids ; but in reiterated connection, an orgasm may occur when the ejaculated 

 fluid has no fecundating properties. 



With regard to the mechanism of erection, little remains to be said after 

 the description that has been given of true, erectile tissue, in connection with 

 the physiology of the circulation. The cavernous and spongy bodies of the 

 penis usually are taken as the type of erectile organs. In these parts the 

 arteries are large, contorted, provided with unusually thick, muscular coats, 

 and are connected with the veins by vessels considerably larger than the true 

 capillaries. They are supported by a strong, fibrous net- work of trabeculae, 

 which contains non-striated muscular fibres ; so that when the blood-vessels 

 are completely filled the organ becomes enlarged and rigid. Eesearches with 

 regard to the nerves of erection show that the vessels of erectile tissues are 

 distended by an enlargement of the arterioles of supply, and that there is not 

 simply a stasis of blood produced by constriction of the veins, except possi- 

 bly for a short time during the period of greatest excitement. In experi- 

 ments upon dogs Eckhard discovered a nerve derived from the sacral plexus, 

 stimulation of which produced an increase in the flow of blood through the 

 penis, attended with all the phenomena of erection. This nerve arises by 

 two roots, at the sacral plexus, from the first to the third sacral nerves, and is 

 connected with the genito-spinal centre, in the lower part of the lumbar re- 

 gion of the spinal cord (Budge). In the experiments referred to, by a com- 

 parison of the quantity of venous blood coming from the penis before and 

 during the stimulation of the nerve, Eckhard found a great increase during 

 erection. It is probable that in addition to the arterial dilatation, when the 

 penis attains its maximum of rigidity there is a certain degree of obstruc- 

 tion to the outflow of blood, by compression of the veins, and that the rigid- 

 ity is increased by contraction of the trabecular muscular fibres of the 

 corpora cavernosa. At the climax of an orgasm, the semen is forcibly dis- 

 charged from the urethra, by spasmodic contractions of the vesiculse seminales 

 and the ejaculatory muscles. Although this is the physiological mechanism 

 of a seminal discharge, friction of the parts, which usually precedes ejacula- 

 tion, is not absolutely necessary, as is shown by the occurrence of orgasm 

 during sleep, which is liable to take place in healthy men after prolonged 

 continence. 



There are some females, in whom the generative function is performed, 

 even to the extent of bearing children, who have no actual knowledge of a 

 true venereal orgasm ; but there are others who experience an orgasm fully 

 as intense as that which accompanies ejaculation in the male. There is, 

 therefore, the important difference in the sexes, that preliminary excitement 

 and an orgasm are necessary to the performance of the generative act in the 

 male, but are not essential in the female. Still there can be scarcely a doubt 



