THE LIVING BIRD 15 



ing off the offending droplet. The simple reflex arc 

 involved obviously has not required the intermedia- 

 tion of the brain which was already destroyed. But 

 in spite of this, another aspect of the experiment is 

 bound to strike us. The response was actually a 

 very complicated rather than a simple thing. The 



Fig. 1. The Reflex Arc 



A: in its simplest form; B: with association neurones inter- 

 posed. Af, afferent (sensory) neurone; As, association neurone; 

 Ef, efferent (motor) neurone; Gl, gland; M, muscle fibre; Sk, 

 tactile corpuscle in skin. 



entire leg with most of its muscles, as well as various 

 muscles of the trunk and other limbs (balance ad- 

 justments) participated. The solution is readily 

 explained. The simple arc referred to above illus- 

 trates the principle rather than the actual fact for 

 interposed between the termination of the sensory 

 fibre and the commencement of the motor, there 



