66 The Mechanistic Conception of Life 



just as the destruction of the mirror might prevent the reflection 

 of light. This comparison, however, of the reflex process in 

 the central nervous system with the reflection of light has, 

 long since, become meaningless, and at present few physiologists 

 in using the term reflex think of its original signiflcance. In- 

 stead of this, another feature in the conception of the term 

 reflex has gained prominence, namely, the purposeful character 

 of many reflex movements. The closing of the eyelid and the 

 narrowing of the pupil are eminently purposeful, for the cornea 

 is thereby protected from hurtful contact with foreign bodies, 

 and the retina from the injurious effects of strong light. 

 Another striking characteristic in such reflexes has also been 

 emphasized. The movements which are produced are so weU 

 planned and coordinated that it seems as though some intelli- 

 gence were at work either in devising or in carrying them out. 

 The fact, however, that even a decapitated frog will brush 

 with its foot a drop of acetic acid from its skin, suggests that 

 some other explanation is necessary. A prominent psychologist 

 has maintained that reflexes are to be considered as the mechani- 

 cal effects of acts of volition of past generations.' The ganglion- 

 cell seems the only place where such mechanical effects could 

 be stored up. It has therefore been considered the most 

 essential element of the reflex mechanism, the nerve-fibers 

 being regarded, and probably correctly, merely as conductors. 



Both the authors who emphasize the purposefulness of the 

 reflex act and those who see in it only a physical process have 

 invariably looked upon the ganglion-cell as the principal bearer 

 of the structures for the complex coordinated movements in 

 reflex action. 



I should have been as little inclined as any other physiolo- 

 gist to doubt the correctness of this conception had not the 

 establishment of the identity of the reactions of animals and 

 plants to light proved the untenability of this view and at the 



1 A statement for whlcli no trace ol experimental proof exists. 



