228 PROFESSOR LIONEL S. BEALE, P.R.C.P., F.R.S,, OK 



cuiitaininii; a larger perceiitag-e of solid matter than does 

 the moist more aetive growing tissue to which I have 

 alluded. This thin layer, extending over the whole of the 

 outer surface of the folded layer of the convolutions of the 

 brain, which in most vertebrata is just beneath the skull, is 

 covered by a delicate, highly vascular membrane, so that 

 the soft part, the grey matter, is supplied Avith a very free 

 distribution of blood of course associated with the free 

 distribution and interchange of nutritive and oxydizing 

 fluid. The action of this part of the nervous system never 

 ceases, from early life to death in old age, in healthy 

 organisms. In other words, the grey matter of the brain, 

 Avliich contains a vast innnber of " cells " or living bioplasts, 

 is active all through life, except in alternating periods of 

 healthy sleep, when it " rests " from action altogether and 

 waste matter is removed. I suppose the reason why we 

 require so much sleep, about one-third part of the twenty- 

 four hours, is to make up for the Avaste Avhich has taken 

 place during the active period of the day, in consequence of 

 the active vital changes Avhich occur in the living matter of 

 the hmumerable " cells " of the grey matter. Now these 

 " cells," to this day have not been sufficiently studied, but 

 I think there is no doubt whatever that they do all the 

 intellectual work of the body, Avhile multitudes are actively 

 concerned in every A^oluntary movement. These " cells " are 

 also the seat of thought and Avill. Indeed in structure and 

 arrangement these " cells " are as elaborate, and are as 

 numerous as Ave should expect to find them considering the 

 Avonderful and highly important Avork they do. If the brain 

 matter concerned in thought, every kind of intellectual action 

 and voluntary movement, is not kept constantly supplied with 

 a large amount of Avater, its action Avill be seriously deranged. 

 By the general arrangement in " convolutions " of the 

 upper part of the human brain, the greatest amount of 

 brain tissue and active brain matter is caused to occupy the 

 smallest space ; and every portion of it is Avell protected 

 from injury. Take a very thin section, say an inch square 

 and not more than the one five-hundredth of an inch in 

 thickness, there will be perhaps fifty thousand or more of 

 these remarkable "cells." Each "cell" is of very striking 

 and complicated structure. From each one of them a large 

 number of very fine nerve fibres proceed. Each " cell " in 

 man is not more than one tAvo-thousandth part of an inch in 

 diameter, and you may, therefore, conceive what milHons 



