The Biochemistry of Semen 



Table 1 . Species differences in volume and sperm density of 

 ejaculated semen 



The two components of semen, sperm and seminal plasma, differ 

 in their origin, composition and function, and must be considered 

 separately, in much the same sense as for instance, blood corpuscles 

 and blood plasma. 



Early investigators of semen were, not unnaturally, fascinated by 

 the spermatozoa, and, with the aid of such optical instruments as 

 were available to them, concentrated their efforts upon the elucida- 

 tion of the structural details of spermatozoa. But it is very much to 

 their credit that they have not entirely neglected the seminal plasma. 

 Thus, the letter in which Antoni van Leeuwenhoek reported in 1 677 

 to the Royal Society on sperm motion, also contains the earliest 

 description of spermin crystals in the seminal plasma. Louis Nicolas 

 Vauquelin, the author of the first treatise on the chemical composi- 

 tion of semen (Experiences sur le sperme humain, 1791), fully appre- 

 ciated the separate existence of sperm and seminal plasma; the same 

 was true of his followers, among them Friedrich Miescher, whose 

 collected writings, published in 1897, contained much new informa- 

 tion concerning not only spermatozoa but the seminal plasma as 

 well. 



The work of Miescher and his contemporaries, however, dealt 

 largely with fish spermatozoa, and even during the early decades of 



