846 



CHEMICAL COMPOSITION OF THE SEMINAL FLUID. 



also fairly largo polyhedral interstitial cells, often with a large nucleus and sometimes 

 pigmented. They represent the residue of the epithelial cells of the Wolffian bodies (Klein), 

 or, according to Waldeyer, they are plasma cells. The blood-vessels are numerous, and form 

 a dense plexus outside the basement membrane of the seminal tubules.] 



Tubulus 



A E&ll!<;\ tubeofepi 

 "J/J didymis. 



rectus 



Blood-vessel. 



\ Transverse 

 ! . section of a 



Blood-vessel 



Interstitial 

 connective- 

 tissue. 



mm 



Bsft>\ Ciliated 

 ^ v __ cylindrical 

 VN, epithelium. 



Fig. 633. Fig. 634. 



Fig. 633. Convoluted seminal tubule opening into a narrow straight tubule. Fig. 634. 

 Transverse section of the tubules of the epididymis. 



Chemical Composition. The seminal fluid, as discharged from the urethra, is 

 mixed with the secretion of the glands of the vas deferens, Cowper's glands, and 

 those of the prostate, and with the fluid of the vesiculae seminales. Its reaction 

 is neutral or alkaline, and it contains 82 per cent, of water, serum-albumin, alkali- 

 albuminate, nuclein, lecithin, cholesterin, fats (protamin?), phosphorised fat, salts 

 (2 per cent.), especially phosphates of the alkalies and earths, together with sul- 

 phates, carbonates, and chlorides. The odorous body, whose nature is unknown, 

 was called "spermatin" by Vauquelin. 



Seminal Fluid. The sticky, whitish -yellow seminal fluid, largely composed of a mixture of 

 the secretions of the above-named glands, when exposed to the air, becomes more fluid, and on 

 adding water it becomes gelatinous, and from it separate whitish transparent flakes. When 

 long exposed, it forms rhomboidal crystals, which, according to Schreiner, consist of phosphatic 

 salts with an organic base (C 2 H 6 N). These crystals (fig. 635) are said to be derived from the 

 prostatic fluid, and are identical with the so-called Charcot's crystals (fig. 149, c, and 138). 

 fne prostatic fluid is thin, milky, amphoteric, or of slightly acid reaction, and is possessed of 

 the seminal odour. The phosphoric acid necessary for trie formation of the crystals is obtained 

 from the seminal fluid. A somewhat similar odour occurs in the albumin of eggs not quite 

 fresh. The non-poisonous ptomain, cadaverin (pentamethyldiamin of Ladenburg), isolated by 

 Brieger from dead bodies, has a similar odour. The secretion of the vesiculae seminales of the 

 guinea-pig contains much fibrinogen (p. 376). 



The spermatozoa are 50 /x long, and consist of a flattened pear-shaped head 

 (fig. 636, 1 and 2, k), which is followed by a rod-shaped middle piece, m 

 (Sckweigger-Seidel), and a long tail-like prolongation or cilium, /. The sperma- 

 tozoon is propelled forwards by the to-and-fro movements of the tail at the rate 

 of 0*05 to 0*5 mm. per second ; the movement is most rapid immediately after 

 the fluid is shed, but it gradually becomes feebler. 



Finer Structure. The observations of Jensen have shown that the middle piece and 

 head are still more complex, although this is not the case in human spermatozoa and those 



