ioG RKPOKT — 1870. 



SuCfGKSTEI) InVESTIKATIOX. 



^^']lat I Dieaii may perhaps be better iindevstood l)y a ic,roarc!i v.liich I wonlil 

 .'^i!gge.;t by 'way of experiment. No one wlio has Itept an aviary of ,'rmall birds — 

 pay a collection of oTir native and foreig'n finches — can have failed toob.?erve marked 

 diiferences of cliaracter and habits among different members of the same genns, and 

 even among diilerent members of the same species. One manifests cunning, another 

 c.imbativeness, a third liindness to smaller brethren, a fourth bullies all about him, 

 a fifth may usually be quiet and peaceable, but occasionally gives way to uncon- 

 trollable rage, and so on. The question arises, then, Have these psychologicnl 

 peculiarities any organic basis, any explanation in the structure of the brain '^ or. 

 Are we to rest satisfied by asserting that these pecidiarities are due to the action 

 of some kind of psycliical principle regarding which we know nothing ? I ha-.c 

 little doubt most will agree that these psychical characteristics of birds depend on 

 peculiarities of brain-structure the result of hereditary transmission through many 

 generations. If so, here we have an opportunity of examining tlie microscopical 

 structure of small brains, relatively simple, and easy of manipulation, with the view 

 of ascertaining whether or not thei'e are any structural differences which may ac- 

 comit for these differences in psychical character. This is a line of inquiry likely, 

 ill my opinion, to establish an organic basis for a comparative psychology. 



Recent Rese.a.hches ox the Chemistry of the Bb.\in. 



But in studying the physiology of the brain as an organ of mind (and the same 

 holds good with regard to the other gre.at nerve-centres) we must not forget that, 

 in addition to mere structure, two other factors have to be taken into notice. These 

 are, first, the chemical constitution of the brain itself; and, second, the amoimt of 

 chemical interchange that goes on between it and the blood. There are so many 

 exceptions to the general ride, that size of brain and number of convolutions are 

 proportional to the degree of mental power, as to render it higlily probable that to 

 accoimt for these exceptions we must assume differences of minute structure, 

 differences of chemical constitution, and differences of chemical interchange between 

 blood and brain. That is to say, we may have two brains equal in size and in number 

 of convolutions belonging to two indi-\iduals very unequal in mental capacity. This 

 may be accounted for either by supposing that the minute structure of a convolu- 

 tion of the one may be more intricate than that of the otlier, or the one brain may 

 be richer in certain complicated chemical compounds, the splitting up of ^\]iicli into 

 simpler bodies is necessary in processes of thought ; or, finall}', the activity of che- 

 mical interchanges between the blood and the brain may be much more rapid in 

 the one than in the other. All this, however, must remain a matter of conjecture 

 rmtil we Imow more of the cliemistry of the brain than we at present do. I liave 

 therefore hailed with satisfaction the appearance of an elaborate paper l)y Dr. 

 Thudicum, entitled, '' Researches on the Chemical Constitution of the Brain," in 

 a recent volume of ' Keports of the Medical OfHcer of tlie Vv\\y Council and Local 

 Government Board.' It is impossible to gi-^-e here a detailed account of this labo- 

 rious inquiry, in which Dr. Thudicum and his assistant, ]\Ir. C. T. Kingzett, ha^■e 

 analyzed the brains of oxen, requiring no fev.-er than a thousand of tliese in the 

 undertaking. The result, generally speaking, has been the discovery of se^■enteen 

 compomids, for the first time detected as ingredients in brain-matter ; and in nn 

 appendix, Dr. Thudicum gives a list of no fewer than eighty-two substances wj!i<'h 

 have been detected, by himself and other chemists, in the brain. Even admitting, 

 what is highly probable, that many of these are products of the decomposition of a 

 few more complex substances, still we obtain from a mere inspection of this lif.t 

 some idea of the intricate chemical nature of tliis part of our bodies. 



Various striking thoughts are put forth by Dr. Thudicum at the end of his paper, 

 a few of which I may be allowed to refer to with the view of shoA\'ing how chemical 

 considerations may assist us in our conceptions of the working of the ner^-ous svs- 

 tem. He says, "During these in'oceedings the first striking fact which meets the 

 inquirer is, that nerve-matter contains abundance of water. This, in conjunction 

 with the peculiar manner in which the water is contained, engenders a mobility of 



