Functions of the Medulla Oblong ata. 615 



formed if the companion trick be forcibly restrained. I have some- 

 where seen an account of the keeper of a Scotch castle who was blind, 

 and who had a habit of canying about a key when he conducted people 

 over the place. When this key was abstracted from him he became so 

 disconcerted as to lose his way. Fumbling the key was so associated 

 with his movements about the structure, that the latter could not take 

 place without the former. The numerous superfluous taps which every 

 blacksmith gives his anvil, afford another illustration of the reflex course 

 of undirected energy along the line of habit. 



But we are also bound to observe that the very same law governs pur- 

 posive action as well as reflex action. The energy will operate in the 

 line of the least resistance, which is still generally the line of habit. 

 The great majority of all our actions are simply imitations of similar 

 ones gone before. We find ourselves every morning under an impulse 

 to do the same things we have done every other morning for years back, 

 As the day wears on we are assailed by a recurrence of the same suc- 

 cession of impulses. Our actions are in detail practical!}' the same day 

 after day, and although we suppose them to be performed in conscious- 

 ness, we shall find, if we attempt to recall them in memory, that by far 

 the greater part of them are not. Our steps in walking, the gestures 

 and movements of our hands and head as they are influenced by the 

 senses of sight and hearing, are, in ninety-nine cases out of a hundred, 

 unconsciously reflex. The habits of ordinary motion are so well estab- 

 lished as to excite consciousness in but a slight degree, and generally 

 not at all. 



The relationships of the different kinds of motion to each other are, 

 in some cases, inconstant and various, and consequently are not habit- 

 ual. It is therefore these relationships which most frequently arouse 

 consciousness. We may know why we walk, and the points of depart- 

 ure and destination, although unable to recount the steps taken, or the 

 commonplace objects encountered on the way. The motive of which 

 we are conscious, and which originates in the higher brain centers, has 

 an effect upon the ganglia of the medulla oblongata in the same way 

 that those stimuli have which come from the environment direct, or 

 from the visceral organs and muscles of the body. Whatever the source 

 of the stimulations which reach the nerve centers of the medulla, these 

 centers inaugurate actions in the parts which they control, in manner and 

 detail entirely machine-like, and independent of the will, so that the 

 purposive actions which require the co-operation of the centers in the 

 medulla oblongata, are purposive only as to the end to be attained, and 

 not the means. The purpose as a stimulus, takes rank alongside of the 

 other stimuli which are competent to touch off the nerve centers ; such 

 as a feather in the throat, or a microbe in the lungs. 



