January 7, 1910] 



SCIENCE 



11 



this process occurs at the age of twenty or 

 eighty years, it is the beginning of senility. 

 And, alas, that this coagulation of the 

 mental powers often takes place so early! 

 Many a boy's brains are curdled and 

 squeezed into traditional artificial molds be- 

 fore he leaves the grades at school. His 

 education is complete and senile sclerosis of 

 the mind has begun by the time he has 

 learned his trade. For how many such 

 disasters our brick-yard methods in the 

 public schools are responsible is a question 

 of lively interest. 



We who seek to enter into the kingdom 

 of knowledge and to continue to advance 

 therein must not only become as little chil- 

 dren, but we must learn to continue so. 

 The problem of scientific pedagogy, then, 

 is essentially this : to prolong the plasticity 

 of childhood, or otherwise expressed, to 

 reduce the interval between the first child- 

 hood and the second childhood to as small 

 dimensions as possible. 



The docile or educational period of a 

 mammal is largely devoted to the progres- 

 sive mechanization of the in-born plastic 

 tissue of the higher correlation centers, i. e., 

 to habit formation, or otherwise expressed 

 to the elaboration of acquired automatisms 

 and reflexes of the type commonly referred 

 to as lapsed intelligence. Much confusion 

 has arisen from the failure to distinguish 

 these individually acquired automatisms 

 from those performed in the hereditary 

 pattern, i. e., lapsed intelligence from true 

 instinct. 



Now to return from this digression, let 

 us consider some data bearing on the phy- 

 logeny of the nervous functions in verte- 

 brates. "We have commented upon the fact 

 that the tubular form of the vertebrate 

 nervous system presents mechanical advan- 

 tages over the ladder-like form of the ar- 

 ticulates for the development of correlation 

 tissue and that the parent type of this 



tissue is found in the central gray and 

 reticular formation which borders the gray 

 matter in the spinal cord. 



The nervous mechanism of the remark- 

 able adaptiveness, the apparent purposeful- 

 ness, of the spinal cord reflexes has been 

 lucidly explained by Sherrington in his 

 Silliman lectures, where he shows that one 

 of the chief functions of the correlation 

 cells of the gray matter (cells of the retic- 

 ular formation type) is the elaboration of 

 a single final common path adapted to 

 serve, as occasion may require, a large and 

 variable number of receptors and afferent 

 paths. Although this apparatus reacts 

 largely in a fixed and invariable mode de- 

 pending on the internal connections of the 

 neurones of which it is composed, never- 

 theless it possesses a certain amount of 

 flexibility growing out of a variable internal 

 resistance at the synapses, or points of 

 physiological union of one nerve cell with 

 another, and particularly the modification 

 of this resistance by practise or habit. 

 This modifiability is not per se evidence of 

 anything psychic ; for we find it in unicel- 

 lular animals and plants with no nervous 

 system and even in many dead mechan- 

 isms; yet this feature is the point of de- 

 parture for those higher types of correla- 

 tion centers which serve as the organs of 

 mind par excellence. 



In the head end of the neural tube there 

 is an obvious tendency for the peripheral 

 nerves serving a single function to con- 

 verge just before or just after they enter 

 the brain so as to reach a single primary 

 center. This concentration of functional 

 systems is obviously advantageous in facil- 

 itating the distribution of afferent impulses 

 to their proper motor organs, especially 

 the total reactions so characteristic of ver- 

 tebrate life as distinguished from the seg- 

 mental reflexes characteristic of worms and 

 insects. The enlargement of these primary 



