THE NERVOUS SYSTEM AND THE INTELLECT. 



279 



to intervene between the spark and the sound of 

 the bell so that the mind may decide whether one 

 comes before the other. That time, according to 

 Donders, would give the time required for form- 

 ing a simple idea — the idea of anteriority. Wheth- 

 er the Utrecht physiologist has gained the end he 

 is pursuing or not, his attempt is not the less one 

 of the most interesting ever made in the analysis 

 of vital phenomena. For the first time the in- 

 most cerebral acts — the intellect — have been sub- 

 jected to instruments and calculations. Perhaps 

 it will be discovered some day that there is a 

 real "slowness of mind," as there is muscular 

 weakness ; perhaps we shall have proof by ex- 

 periment that other brains, in the simplest opera- 

 tions, have a quickness of appreciation, a liveli- 

 ness of determination, whose estimate the instru- 

 ments of the future may give us in figures. We 

 hardly know where we shall stop in the path 

 marked out by the eminent physiologist with his 

 instruments of outlandish name. 



While physics were thus invading the domain 

 of ancient metaphysics, the latter being probably 

 greatly astonished at the intrusion, chemistry, 

 for its part, has not been backward. It is a fixed 

 law in biology that the manifestation of any vital 

 peculiarity whatever, such as secretion by a gland, 

 contraction of a muscle, is necessarily attended 

 by a chemical change in the tissue at work. The 

 nerve-matter, certainly, is not excepted from this 

 general absolute law. There is no doubt that 

 the act of thinking, reflecting, grouping ideas 

 or reasoning, is attended by a more or less per- 

 ceptible but sure modification in the chemical 

 composition of the gray matter; but how can 

 we reach the discovery of this ? We cannot avail 

 ourselves of animals. Whatever a hare in his 

 form may be thinking of, there is no proof that 

 he really is thinking. Thought while awake 

 sometimes reveals itself by gestures and atti- 

 tudes ; but these signs indicate no certain thing, 

 and the sleep calmest to appearance may be 

 haunted by the most excited dreams. For him- 

 self alone each one is aware of his own cerebral 

 activity: therefore, experiments must be made 

 on one's self. The difficulty is serious ; research 

 into the functions of the nervous system is 

 always delicate and minute, even when the end 

 aimed at is clearly understood. What will it be 

 when experimenting must be blended with the 

 search for the unknown ? We should, doubtless, 

 be completely ignorant of the chemical modifica- 

 tions attending mental action, were it not for the 

 devotion of a young student who purposely sub- 

 jected himself for quite a long time to a pure- 



ly experimental existence, like Santorio in his 

 scales. That famous doctor of Padua doomed 

 himself to weigh himself at almost each hour of 

 the day, to weigh every article of food taken, 

 every excretion. Engravings of the period rep- 

 resent him sitting at a table in a sort of balance, 

 looking at the needle which marks the increase 

 of weight occasioned by every mouthful. By- 

 asson restricted himself for some time to a still 

 more monotonous mode of life. He set out with 

 the reasoning that the residue of the chemical 

 combinations that occur in the body passes al- 

 most entirely through the kidneys. He conceived 

 the idea of examining at that point whether the 

 cerebral activity of the centres would not be there 

 represented by some variation in the nature or 

 quantity of the excreted saline products. Before 

 any definite research was begun, his first care was 

 to remove any disturbing cause, and to make 

 comparisons possible. For this it was necessary 

 to insure a most troublesome uniformity in his 

 life. The young observer subjected himself to 

 this with a degree of courage that deserves the 

 gratitude of science. He began by absolute se- 

 clusion from intercourse with any one. His time 

 was imperatively regulated, and the whole day 

 divided between settled occupations and the un- 

 ceasing analyses he was obliged to make. For 

 his only nourishment, he took daily twenty-six 

 ounces of biscuit (because bakers' bread might 

 vary every day), and sixteen ounces of water, 

 which he provided beforehand, because springs 

 do not always yield the same quality. When this 

 regimen had brought about daily uniformity in 

 the action of the organs, Byasson, at length, be- 

 gan his experiments. They lasted four days. 

 The first two, he devoted himself to violent mus- 

 cular exercise, not calculated to engage the mind, 

 snch as digging in the garden, and carrying up 

 wood. The third day was given almost wholly 

 to mental labor, problems in analytical geometry, 

 and reading a work on physiology. The fourth 

 day, in fine, and the last, was given up to abso- 

 lute rest in silence and darkness. Byasson suc- 

 ceeded in ascertaining, by exact analyses, that 

 the mental labor of the third day was represented 

 by a waste greater than the supply furnished, of 

 certain saline principles, different from those ex- 

 creted by the body after muscular exercise or 

 perfect rest. He therefore believed the conclu. 

 sion to be correct that these saline principles 

 originated in the chemical reactions that take 

 place in nerve-matter when it is at work. 



Do we mean to say, then, that modern biolo- 

 gy, which as we see pursues so closely the most 



