SEMINAL FLUID. 349 



when it is mixed with water ; the mixture is not rendered appre- 

 ciably more turbid by boiling, but alcohol induces perfect coagula- 

 tion. 



In animals, during the period of heat the seminal fluid may be 

 collected in comparatively large quantities from the vasa deferentia 

 and the vesiculae seminales ; the latter, however, secrete an inde- 

 pendent fluid, and hence we often find no true seminal fluid in 

 them. 



This fluid contains the most remarkable morphological elements 

 which we meet with in the animal organism, the seminal animalcules 

 or spermatozoa. These elements which, according to the unani- 

 mous evidence of physiologists, occur in the fruitful seed of all 

 animals, have in most cases tolerably similar although distinguish- 

 able forms; there is a round, oval, or pyriform head, to which is 

 attached a long filament gradually coming to a point. With 

 regard to the dimensions of these singular formations, the head in 

 man varies in breadth from 0*0007'" to 0*0013"', and in length from 

 0-0019'" to 0*0025'", while the filament or tail has a length varying 

 from 0*0018'" to 0*0020'". The greatest peculiarity in connection 

 with these structures is their apparently spontaneous motion, which 

 for a long time led to the belief that they were infusoria; the 

 continuous motion appears to be produced by the bending and 

 rapid stretching of the tail from one side to the other, so that the 

 molecule moves in a zigzag direction, following the course of its 

 head. This power of motion is often retained for a long time if 

 the semen be protected from evaporation, or when it is placed in 

 tepid s^rum, urine, saliva, or mucus ; if the seminal fluid be mixed 

 with double its quantity of water, the filaments lose their power of 

 motion, and become more or less rolled up (Henle,* R. Wagnerf). 

 The motion is destroyed by decomposition of the semen, by spirits 

 of wine, a solution of opium, and strychnine ; the tail then gene- 

 rally remains extended. The spermatozoa are not readily destroyed 

 by putrefaction ; they are dissolved by concentrated but not by 

 dilute solutions of the alkaline carbonates ; the latter solutions, on 

 the other hand, often render them more distinct under the micro- 

 scope, by dissolving the coagula or mucus occurring between them. 

 When carefully exposed to a great heat, they leave, according to 

 Valentin, an ash, which retains their precise form. 



There are likewise other morphological elements besides the 

 spermatozoa which occur in the semen ; in addition to scattered 



* Allg. Anatom. S. 949958. 



f Lehrb. d. spec. Phys. 3te Aufl. 1845, S. 49. 



