THE ACTIVE FORCES OF LIVING ORGANISMS 21 



the behaviour of this element in the animal economy 

 opinions differ greatly. Some look upon its presence 

 in the brain and elsewhere as without any special 

 meaning ; others are disposed to regard it as a factor 

 of importance in vital processes. That it is a very 

 active element is undeniable, and although in certain 

 insoluble or slightly soluble compounds this activity 

 may disappear, yet there is no reason to suppose 

 that it plays a quiescent or secondary part in cerebral 

 matter, in the nuclei of cells and in the yolk of egg. 

 These are at all times centres of great activity, and it 

 seems improbable that the element phosphorus, which 

 in the free state has so great an af&nity for oxygen, 

 should remain inactive at such moments, or even rela- 

 tively so. Some authorities hold that, after severe 

 mental exertion, the amount of phosphates in the 

 urine is increased. By others this is denied. Although 

 on general grounds one may suppose the former to 

 be in the right on this point, yet, if the amount of 

 phosphorus liberated during cerebral action is at all 

 in proportion to the quantity of -carbonic acid formed, 

 any increase of the former due, as there is reason to 

 suppose, to the breaking down of lecithin* would be 

 very slight. Sometimes, however, when abnormally 

 large quantities of phosphates are present in the 

 urine, it is not improbable that this is due to a greatly 

 relaxed condition of the tissues in general and of the 

 bloodvessels to the nerve centres, whereby metabolism 



* Foster, loc. cit, p. 651. 



