GENERAL LAW OF ANIMAL FERTILITY. 597 



cant; and the fact that in the same individual the varying 

 degrees of cerebral activity are indicated by the varying quanti- 

 ties of alkaline phosphates excreted by the kidneys,* still more 

 clearly shows the essentialness of phosphorus as a constituent of 

 nervous matter. Respecting the constitution of sperm-cells 

 chemists do not altogether agree. One thing, however, is certain 

 that they contain unoxidized phosphorus; and also a fatty 

 acid, that is not improbably similar to the fatty acid contained in 

 neurine.f In fact, there would seem to be present the con- 

 stituents of that oleophosphoric acid which forms so distinctive 

 an element of the brain. That a large quantity of binoxide of 

 protein is also present, may be ascribed to the fact that a great 

 part of the sperm-cell consists merely of the protective membrane 

 and its locomotive appendage ; the really efficient portion being 

 but the central contents.^ 



Evidence of a more conclusive nature evidence, too, which 

 will show in what direction our argument tends is seen in the 

 marked antagonism of the nervous and generative systems. 

 Thus, the fact that intense mental application, involving great 

 waste of the nervous tissues, and a corresponding consumption of 

 nervous matter for their repair, is accompanied by a cessation in 

 the production of sperm-cells, gives strong support to the hypo- 

 thesis that the sperm-cells consist essentially of neurine. And 

 this becomes yet clearer on finding that the converse fact is true 

 that undue production of sperm-cells involves cerebral inac- 

 tivity. The first result of a morbid excess in this direction is 

 headache, which may be taken to indicate that the brain is out of 

 repair ; this is followed by stupidity ; should the disorder con- 

 tinue, imbecility supervenes, ending occasionally in insanity. 



That the sperm-cell is co-ordinating matter, and the germ- 

 cell matter to be co-ordinated, is, therefore, an hypothesis not 

 only having much a priori probability, but one supported by nu- 

 merous facts. 



13. This hypothesis alike explains, and is confirmed by, the 

 truth, that throughout the vertebrate tribes the degree of fertility 

 varies inversely as the development of the nervous system. 



* "Lectures on Animal Chemistry." By Dr. Bence Jones. Medical 

 Times, Sept. 18th, 1851. See also Prin. of Phys., p. 171. 



\ Cyclopaedia of Anatomy and Physiology, Vol. IV, p. 506. 



j From a remark of Drs. Wagner and Leuckart this chemical evidence 

 seems to have already suggested the idea that the sperm-cell becomes 

 "metamorphosed into the central parts of the nervous system." But 

 though they reject this assumption, and though the experiments of Mr. 

 Newport clearly render it untenable, yet none of the facts latterly brought to 

 lijlht conflict with the hypothesis that the sperm-cell contains unorganized 

 co-ordinating matter. 

 39 



