BIOPSYCHOLOGICAL 631 



neurons, at once sensory and motor, and the muscle-cells. But when 

 the nestling bird opens its mouth at the touch of the food in its 

 mother's bill, and then proceeds to swallow, this is a compound 

 reflex action. In this typical case there are four links in the chain: 

 (i) the sensory neurons with nerve-endings in the bill; {2) the associa- 

 tive neurons, in the medulla of the brain in this particular case, but 

 oftener in the spinal cord; (3) the motor neurons in the medulla, 

 whose fibres pass to the muscles (4) that open the mouth. More 

 than that, however; for the opening reflex (A) pulls the trigger of 

 the gripping reflex [B), and that in turn of the swallowing reflex (C), 

 and so on it goes. Recalling S for sensory, A for associative, M for 

 motor, and E for effector, S-A-M-E leads to s-a-m-e, and that to 

 s-a-m-e. 



The question rises here whether psychical activity has anything 

 to do with reflexes, or is this a level at which it is entirely un- 

 necessary to complicate description by dragging in "latent men- 

 tality" and other factors? — terms which are so apt to degenerate 

 into verbal abstractions without any factual content, as "natural 

 selection" has often done, and "heredity" and "variation" as well. 

 The point is whether reflex actions can be studied whole, without 

 any reference to the psychical side. Our answer is again a cautious 

 negative, cautious because the physiological description here goes 

 such a long way towards being complete in itself. 



It must be noted that reflex actions are not absolutely inevitable. 

 In certain cases the natural response — organically prepared for — 

 can be inhibited, not merely in the human fugitive who suppresses 

 a betraying cough or sneeze, but in the higher instances of "feigning 

 death", as in the fox, where there may be a suppression of the 

 natural reaction to a blow or a kick. The partly engrained, partly 

 habituated suppression of a natural reaction in pointer dogs is 

 well known, and the habituated control of reflexes is a common 

 feature in training animals. Now the intervention of control in a 

 physiological sequence is one of the surest signs of "mind". 



Another consideration is whether it is possible to picture the 

 evolution of reflex actions, without allowing for some variable 

 degree of awareness and controlled testing on the part of the indi- 

 vidual animal, and this throughout the generations during which 

 the increased neuro-muscular differentiation and integration took 

 organismal grip. 



Let us state our position again: if it be granted that a germinal 

 variation may express itself in structural improvements in the body, 

 including the nervous system, there is no particular difficulty in 

 imagining the origin of reflex arcs and actions. When the rapidity 

 and precision of the response is of survival value, the racial estabhsh- 

 ment of an improved reflex linkage is not difficult to understand. 

 Yet the problem is perhaps unnecessarily obscured by excluding 



