102 PSYCHOLOGY. 



pliospliorus to tlioiiglit would be to find whether more is 

 excreted by the brain during mental activity than during 

 rest. Unfortunately we cannot do this directly, but can 

 only gauge the amount of PO^ in the urine, which repre- 

 sents other organs as well as the brain, and this procedure, 

 as Dr. Edes says, is like measuring the rise of water at the 

 mouth of the MississijDpi to tell where there has been a 

 thunder-storm in Minnesota.* It has been adopted, how- 

 ever, by a variety of observers, some of whom found the 

 phosphates in the urine diminished, whilst others found 

 them increased, by intellectual work. On the wdiole, it is 

 impossible to trace any constant relation. In maniacal 

 excitement less phosphorus than usual seems to be excreted. 

 More is excreted during sleep. There are differences be- 

 tween the alkaline and earthy phosphates into which I will 

 not enter, as my only aim is to show that the popular way 

 of looking at the matter has no exact foundation. f The 

 fact that phosphorus-preparations may do good in nervous 

 exhaustion proves nothing as to the part played by phos- 

 phorus in mental activity. Like iron, arsenic, and other 

 remedies it is a stimulant or tonic, of whose intimate work- 

 ings in the system we know absolutely nothing, and which 

 moreover does good in an extremely small number of the 

 cases in which it is prescribed. 



The phosphorus-philosophers have often compared 

 thought to a secretion. " The brain secretes thought, as the 

 kidneys secrete urine, or as the liver secretes bile," are 

 phrases which one sometimes hears. The lame analogy 

 need hardly be pointed out. The materials which the brain 

 pours info the blood (cholesterin, creatin, xanthin, or what- 

 ever they may be) are the analogues of the urine and the 

 bile, being in fact real material excreta. As far as these 

 matters go, the brain is a ductless gland. But we know of 

 nothing connected with liver- and kidney-activity which can 



* Arcbivcs of Medicine, vol. x, No. 1 (1883). 



f Without multiplying references, I will simply cite Mendel (Arcbiv f. 

 Psychiatric, vol. iii, 1871), Mairet (Archives de Neurologic, vol. ix, 1885), 

 and Beauuis(Rech. Experimentales sur rActiviteCerebrale, 1887). Richet 

 gives a partial bibliography in the Revue Scientifique, vol. 38, p. 788 (1886). 



