iv THE GENERATIVE SYSTEM OF THE MALE 149 



rhythmical manner until all the semen is ejaculated from the 

 rneatus externus of the urethra. On this rhythm in the contraction 

 of the muscles of expulsion depends the emission of the seminal 

 fluid in jets. 



VI. In treating of the sexual instinct (vide Vol. IV. Chap. II. 5, 

 pp. 78-91) we described the phenomenon of puberty, and indicated 

 the central. and peripheral conditions of the several senses which 

 determine sexual excitement, and finally the active intervention of 

 almost the whole nervous system, both central and peripheral, 

 of animal life, directed to promote the physiological processes 

 which secure the fundamental phenomenon of fertilisation of the 

 ovum and the consequent reproduction of the species. Here it 

 only remains to complete the treatment of the subject, to consider 

 especially the nervous pathways and centres on which the reflexes, 

 erection of the penis, and ejaculation of the seminal fluid 

 depend. 



The different central and peripheral stimuli evoke spermatic 

 ejaculation, the more easily and tumultuously the greater the 

 abundance of the accumulated secretions and the tension which 

 they produce in the seminal passages and the corresponding 

 glands. According to the observations of Lode, accumulation of 

 the secretions does not go on continually during abstinence, but is 

 suspended after some days. During prolonged abstinence the 

 secretions are probably reabsorbed only to a small extent by the 

 lymphatic ducts, because spontaneous pollutions occur normally 

 during sleep, accompanied almost always by erotic dreams so vivid 

 as to leave remembrance and sometimes to cause awakening. 

 After puberty, and generally during early manhood, these pollutions 

 occur somewhat regularly every two or three weeks in individuals 

 who are chaste and abstinent. With the first pollution of spon- 

 taneous origin or provoked by masturbation puberty is initiated in 

 the male, as with the first menstruation in the female ; it 

 occurs usually about a year later in the former than in the latter, 

 and in our climate at the age of about fourteen to fifteen years. 

 The normal generative capacity ceases in woman at the so-called 

 climacteric age, whilst in man it is prolonged usually to a very 

 advanced age, and does not cease entirely until extreme old age. 



The reflex centres for erection and ejaculation are, according 

 to the great majority of physiologists, situated in the lower 

 segments of the lumbar spinal cord. From the experiments of 

 Goltz on dogs (1874) it is evident that after transverse section of 

 the spinal cord between the last dorsal and first lumbar vertebra, 

 and the disappearance of the depressing effects of the operation, 

 it is possible by friction of the penis, or suitable mechanical 

 stimulation of the skin of the perineal region, to provoke not only 

 the phenomenon of erection, but also that of spermatic ejaculation. 

 When the bladder of the dog is full, it is sufficient sometimes to 



VOL. V L 3 



