1 68 The Biochemistry of Semen 



prostatic secretion, whereas the phosphoric acid is derived from 

 some other source. Recent advances in this field favour this hypo- 

 thesis and indicate that the formation of spermine phosphate takes 

 place only after the ejaculation, as the outcome of a reaction be- 

 tween spermine which is contributed by the prostatic secretion, and 

 phosphoric acid, which accumulates gradually through the action 

 of the seminal phosphatases upon phosphorylcholine and perhaps 

 also upon some other organic phosphorus compounds. 



CHOLINE 



The Florence reaction in semen 



Florence, working in the laboratory of forensic medicine in Lyons, 

 made the following observation in 1895; if material stained with 

 ] luman semen is extracted with water, and a drop of this extract is 

 mixed on a microscopic slide with a strong solution of iodine in 

 potassium iodide (2-54 g. I2, 1-65 g. KI, 30 ml. water), the micro- 

 scopic field is quickly filled with a mass of brown crystals which 

 ]-esemble closely Teichmann's crystals of haemin. Florence's treatise 

 'Du sperme et des taches de sperme en medecine legal' (1895/96) 

 created much interest in forensic medicine and led promptly to the 

 lecognition of his test as a useful means for the identification of 

 seminal stains. At first, a hypothetical substrate called 'virispermine' 

 was held responsible for the formation of 'iodospermine' in the 

 Florence reaction, but later on other substances came under investi- 

 gation, including choline. All doubts concerning the nature of the 

 Florence's reaction product were finally dispelled when Bocarius 

 (1902) succeeded in converting 'iodospermine' preparations ob- 

 tained from human and stallion semen, into a crystalline platinum 

 compound which contained 31-62% Pt and was identical in every 

 way with pure choline platinum chloride (31-64% Pt). Stanek's 

 work in Prague (1905, 1906) had shown that the iodine compound 

 formed in Florence's reaction was a water-insoluble periodide of the 

 composition of an enneaiodide, corresponding to the formula 

 QHuNOFIg. The method developed by Stanek for the quantitative 

 determination of choline depended on the analysis of nitrogen 

 (Kjeldahl) in the periodide precipitate; the more recent quantitative 



