208 



♦ KNOAA^LEDGE ♦ 



[August 1, 1889. 



emigrants include the highest proportion of children (22 per 

 cent, last year), the Irish the least (108 per cent.). The 

 great bulk of the English emigration is from Liverpool, that 

 of the Scotch from Glasgow and Greenock, that of the Irish 

 from Qaeenstown. Of the adults emigratintr last year, some 

 80,000 are described as " general labourers," i9,000 (female) 

 " domestic and farm servants, niirses, &c.," 24,000 " agricul- 

 tural labourers, gardeners, carters, <tc.," 20,000 " mechanics," 

 14,000 "gentlemen, professional men, merchants, &c.," 

 11,000 "farmers and graziers," 5,000 " miners and quany- 

 men," 3,000 " clerks and agents," .1,000 " shopkeepers," and 

 so on. 



GROWTH AND DECAY OF MIND. 



By the late E. A. Proctor. 



And so from hour to hour we ripe and ripe. 

 And then from hour to hour we rot and rot, 

 And thereby hangs a tale. — As You Like It. 



EW subjects of scientific investigation are 

 more interesting than the inquiry into the 

 various circumstances on which mental 

 power depends. By mental power I do 

 not mean simply mental capacity, or the 

 potential quality of the mind, but the 

 actual power which is the resultitnt, so to 

 speak, of mental capacity and mental 

 training. The growth and development of mental power 

 in the individual, and the process by which, after attaining 

 a maximum of power, the mind gradually becomes less 

 active, until in the course of time it undergoes at least a 

 partial decay, form the special subjects of which I propose 

 now to treat ; but in order to form clear ideas on these 

 subjects it will be necessary to consider several associated 

 matters. In particular, it will be desirable to trace the 

 analogy which exists between bodily and mental power, not 

 only as respects development and decay, but \vith regard to 

 the physical processes involved in their exercise. 



It is now a well-established physiological fact that mental 

 action is a distinctly physical process, depending primarily 

 on a chemical reaction between the blood and the brain, 

 precisely as muscular action depends primarily on a chemical 

 reaction between the blood and the muscular tissues. With- 

 out the free circulation of blood in the bmin there can be 

 neither thought nor sensation, neither emotions nor ideas. 

 It necessarily follows that thought, the only form of brain 

 action which we have here to consider, is a process not 

 merely depending upon, but in its turn affecting, the 

 physical condition of the brain, precisely as muscular exer- 

 tion of any given kind depends on the quality of the muscles 

 employed and affects the condition of those muscles, not at 

 the moment only, but thereafter, conducing to their growth 

 and development if wiseh' adjusted to their power, or 

 causing waste and decay if excessive and too long continued. 

 It is important to notice that this is not a mere analogy. 

 The relation between thought and the condition of the brain 

 is a reality. So far as this statement affects our ideas about 

 actually existent mental power, it is of little importance ; 

 for it is not more useful to announce that a man with a good 

 brain will possess good mental powers than to say that a 

 muscular man will be capable of considerable exertion. 

 But as it is of extreme importance to know of the relation 

 which exists between muscular exercise and the growth or 

 development of bodily strength, so it Ls highly important for 

 us to remember that the development of mental power depends 

 largely on the exercise of the mind. There is a " training " 

 for the brain as well as for the body — a real physical training 

 — depending, like bodily training, on rulesas to nourishment, 

 method of action, quantity of exercise, and so forth. 



When we thus view the matter, we at once recognise the 

 significance of relations formerly regarded as mere analogies 

 between mental and bodily power. Instead of saying that 

 as the body fails of its fair gi-owth and development if over- 

 taxed in early youth, so the mind suffers by the attempt to 

 force it into precocious acti\-ity, we should now say that the 

 mind suffers in this case in the same actual manner — that 

 is, by the physical deterioration of the material in and 

 thi'ough which it acts. Again, the old adage, " mens sana 

 in corpore sano," only needs to be changed into " cerebrum 

 sanum in corpore sano," to express an actual physical 

 reality. The processes by which the brain and the body 

 are nourished, as well as those which produce gradual 

 exhaustion when either is employed for a long time or on 

 arduous work, not only correspond with each other, but are 

 in fact identical in their nature ; so that Jeremy Taylor 

 anticipated a comparatively recent scientific discovery when 

 he associated mental and bodily action in the well-known 

 apophthegm, " Everj' meal is a rescue from one death and 

 lays up for anotlier ; and while we think a thought we die." 

 This is true, as Wendell Holmes well remarks, " of the 

 brain as of other organs : the brain can only live by dying. 

 We must all be born again, atom by atom, from hour to 

 hotir, or perish all at once beyond repair." 



And here it is desirable to explain distinctly that the 

 relations between mind and matter which we are consider- 

 ing are not necessarily connected with any views respecting 

 the questions which have been at issue between materialism 

 and its opponents. We are dealing here with the instru- 

 ment of thought, not with fhat, whatever it may be, which 

 sets the instrument in motion and regulates its operation. 

 So far indeed as there is any connection between physical 

 researches into the nattire of the brain or its employment 

 in thought, and our ideas respecting the individuality of the 

 thinker, the evidence seems not of a nature to alarm even 

 the most cautious. Thus when Huxley maintains that 

 thought is "the expression of molecular changes in that 

 matter of life which Ls the sotirce of our other vital pheno- 

 mena," we are still as far as ever from knowing where 

 resides the moving cause to which these changes are due. 

 We have found that the instrument of thought is moved 

 by certain material connecting links before unrecognised ; 

 but to conclude that therefore thought is a purely material 

 process, is no more necessarily just than it would he to con- 

 clude that the action of a steam-engine depends solely on 

 the eccentric which causes the alternation of the steam- 

 supply. Again, we need find nothing very venturesome in 

 Professor Haughton's idea, that " otu' successors may even 

 dare to speculate on the changes that converted a crust of 

 bread, or a bottle of wine, in the brain of Swift, ISIoliere, 

 or Shakspeare, into the conception of the gentle Glum- 

 dalclitch, the rascally Sganarelle, or the immortal Falstaff," 

 seeing that it would still remain unexplained how such 

 varj-ing results may arise from the same material processes, 

 or how the selfsame fuel may produce no recognisable 

 mental results. The brain does not show in its constitu- 

 tion why such differences should exist. " The lout who lies 

 stretched on the tavern-bench," says Wendell Holmes, 

 " with just mental activity enough to keep his pipe from 

 going out, is the unconscious tenant of a laboratory where 

 such combinations are being constantly made as never 

 Wohler or Berthelot could put together : where such fabrics 

 are woven, such colours dyed, such problems of mechanism 

 solved, such a commerce carried on with the elements and 

 forces of the outer universe, that the industries of all the 

 factories and trading establishments in the world are mere 

 indolence, and awkwardness, and unproductiveness, com- 

 pared to the miracidous activities of which his lazy bulk is 

 the unheeding centre." Yet the conscious thought of the 



