110 PSYCHO LOGY. 



and fix the impressed inoditicatiou, rather than to counter- 

 act it by renewing the original constitution of the tissue 

 that has been impressed. Tlius, we notice after exercising 

 our muscles or our brain in a new way, that we can do so 

 no longer at that time ; but after a day or two of rest, when 

 we resume the discipline, our increase in skill not seldom 

 surprises us. I have often noticed this in learning a tune ; 

 and it has led a German author to say that we learn to swim 

 during the winter and to skate during the summer. 

 Dr. Carpenter writes :* 



" It is a matter of universal experience that every kind of framing 

 for special aptitudes is both far more effective, and leaves a more per- 

 manent impress, when exerted on the growing organism than when 

 brought to bear on the adult. The effect of such training is shown in 

 the tendency of the organ to ' grow to ' the mode in which it is habitually 

 exercised ; as is evidenced by the increased size and power of particular 

 sets of muscles, and the extraordinary flexibility of joints, which are 

 acquired by such as have been early exercised in gymnastic perfor- 

 mances. . . . There is no part of the organism of man in which the 

 reconstructive activity is so great, during the whole period of life, as it 

 is in the ganglionic substance of the brain. This is indicated by the 

 enormous supply of blood which it i-eceives. ... It is, moreover, a 

 fact of great significance that the nerve-substance is specially dis- 

 tinguished by its reparative power. For while injuries of other tissues 

 (such as the muscular) which are distinguished by the speciality of their 

 structure and endowments, are repaired by substance of a lower or less 

 specialized type, those of nerve-substance are repaired by a complete 

 reproduction of the normal tissue ; as is evidenced in the sensibility of 

 the newly forming skin which is closing over an open wound, or in the 

 recovery of the sensibility of a piece of 'transplanted' skin, which has 

 for a time been rendered insensible by the complete interruption of the 

 continuity of its nerves. The most remarkable example of this repro- 

 duction, however, is afforded by the results of M. Brown-Sequard's+ 

 experiments upon the gradual restoration of the functional activity of 

 the spinal cord after its complete division ; which takes place in a way 

 that indicates rather a reproduction of the whole, or the lower part of 

 the cord and of the nerves proceeding from it, than a mere reunion of 

 divided surfaces. This reproduction is but a special manifestation of 

 the reconstructive change which is always taking place in the nervous 

 system ; it being not less obvious to the eye of rea.son that the ' waste ' 

 occasioned by its functional activity must be constantly repaired by the 



* • Mental Physiology ' (1874.) pp. 339-345. 



f[See. later, Masius in Van Benedens' and Van Bambeke's 'Archives 

 de Bioiogie," vol. i (Liege, 1880).— W. J.] 



