STUDY PHYSIOLOGICALLY CONSIDERED. 641 



them permanently in the memory. The inherent vigor of the mind 

 can be strengthened by systematic exercise, just as the muscles of a 

 blacksmith's arm become strong and brawny by years of daily toil at 

 the clinking anvil. 



Throughout animated nature, a period of repose succeeds one of 

 activity, both recurring in regular alternation. The vegetable world 

 grows and blooms ; then, for a season, all the vital processes stand still. 

 Work brings weariness, which rest must dissipate. So is it with the 

 tissues of the body ; and the younger and more delicately organized 

 they are, the sooner does toil exhaust them. Brain-matter is the most 

 delicate of all our tissues, and nearly one third of the pure blood 

 thrown out by the heart at each contraction goes to supply it. A 

 tissue, when at work, has its blood-supply largely increased. When 

 the mind is actively engaged in study, the circulation in the brain is 

 full and active, the temperature is raised, even the face is flushed ; 

 and the more difficult the study, the more these effects are intensified. 

 After a time, the brain becomes so engorged with blood that its activ- 

 ity is depressed and its energies begin to flag. The younger a pupil 

 is, the sooner does his mind grow tired. Between the ages of six and 

 seven, the lessons should not exceed ten minutes' duration, as young 

 children are unable to keep their attention fixed upon one subject for 

 a greater length of time. It may be laid down as a safe rule, that 

 close mental application for an hour and a half will tire out the ma- 

 jority of pupils, and leave them unfit and indisposed to proceed further 

 without a relaxation of at least ten or fifteen minutes. 



Here the forenoon recess is indicated not, as some imagine, simply 

 to kill time, but as a positive physical necessity, not for the pupil 

 alone, but also for the teacher. The worry and mental strain of gov- 

 erning a roomful of nervous, restless children, and teaching at the 

 same time, no one can fully realize without actual experience. 



How should recess be spent by the pupil ? To reply to this, his 

 physical condition must be considered. As the blood is contained in 

 a series of closed vessels, it is evident that, if the circulation be in- 

 creased in one portion, it is correspondingly diminished in another. 

 When the brain is engorged, some other portion of the economy must 

 be under-supplied. By a wise provision of Nature, the surplus is 

 drawn from the tissue that is least active in this case, from the mus- 

 cular system. The indication is to relieve the congested brain, and 

 this is best met by muscular exercise, as a tissue in action has its 

 blood-supply largely increased. The muscular system is of consider- 

 able extent, and the exercise that brings the most muscle into action 

 is the most beneficial. 



Therefore, daring recess, nothing can take the place of active exer- 

 cise in the open air. 



But if the temperature is very low, recess had better be taken in- 

 doors, for the intense cold exhausts the vitality by drawing largely 



VOL. XXIV. 41 



