126 PHYSIOLOGY CHAP. 



minutes after emission it takes a gelatinous form, but a few 

 minutes later it becomes more fluid and remains less viscous. It 

 contains 90 per cent of water and 10 per cent of solid substances. 

 Of the latter, the greatest part is represented by mucin and the 

 remainder by salts, proteins, and extractives. The spermatozoa 

 contain besides proteins, nuclein, nucleic acid, nuclein bases, 

 cerebrosin (akin to cerebrin), also cholesterol, lecithin, and 

 traces of fats and salts. 



The chemical composition of salmon sperm, which can be 

 obtained in great quantities, was well studied by Miescher (1874). 

 According to Posner (1888) the spermatic fluid contains also an 

 albumose and spermin (to which is due the characteristic odour) 

 which arise from the prostatic secretion. 



The spermatozoa contained in a cubic centimetre of semen are 

 very variable in number. According to the observations of Lode 

 (1891) they diminish gradually until they disappear altogether in 

 ejaculations which follow one another rapidly. It is found, 

 however, that after an interval of two days the number of 

 spermatozoa contained in the seminal fluid is greater than after a 

 suspension of sexual intercourse for six days. According to Lode 

 the average number is about 60,000 per cubic millimetre and 

 the total number in a normal ejaculation would reach the average 

 figure of 226 millions. The greatest number of spermatozoa 

 contained in an ejaculation would be 551 millions the least 0. 



The complete absence of spermatozoa in the seminal fluid 

 (azoospermia), in cases in which it does not depend on premature 

 ejaculations rapidly succeeding one another, has been described as a 

 pathological condition during which there may be seminal ejacula- 

 tions more or less normal in manner and quantity, but without 

 any fertilising power. 



The spermatozoa contained in seminal tubes of the testicle and 

 epididymis are immobile, while those in the semen move in a 

 lively manner. Their mobility, therefore, is due to the secretions 

 of the spermatic passages with which they are mingled during the 

 act of ejaculation. The form of movement in the spermatozoa is 

 similar to that which is observed in many flagellate protozoa. 



It is a movement determined by the rapid bending and 

 extension of the tail, whilst the head is inactive and is pushed 

 forward (Hensen). Owing to the velocity of the movements an 

 exact analysis of them is impossible in semen recently ejaculated. 

 Nagel has observed in some spermatozoa a rotation along their 

 longitudinal axis, so as to give a boring effect with the tapered 

 extremity of the head, which some designate the perforcttorium. 

 The oscillatory as well as the rotary movements are considered by 

 him as effects of the resistances opposed to progressive locomotion. 

 According to Lott (1871) the velocity of movement of spermatozoa is 

 0*06 mm. per second, that is, 3*6 mm. per minute. This harmonises 



