346 STUDIES IN GENERAL PHYSIOLOGY 



has the further advantage of being satisfied by a single experiment, 

 in so far as, of the two elements of which the definition is com- 

 posed, the one element is always given anatomically. This is the 

 higher sensory nerve, the presence of which guarantees its func- 

 tion. The only experiment which it is necessary to perform has to 

 prove that the general center of locomotion is also present beside 

 the sensory apparatus. This proof is furnished when the unilateral 

 removal of the central nervous portion in question so alters the 

 direction of the movement of the animal that it no longer moves 

 in a straight line but in a circle a phenomenon which is generally 

 designated by the term " forced movements." 



This definition of Steiner leads to two new conclusions: 

 first, that the cerebrum in human beings does not belong to 

 the brain since, as is well known, unilateral removal does 

 not, bring about forced movements. Steiner himself realizes 



O 



this, for he has found, aided by his definition, that the octo- 

 pus "has a cerebrum but no brain." "To have no brain 

 and yet a cerebrum seems strange and even paradoxical, 

 probably only , however, because we have not until now encoun- 

 tered such a case." The second necessary conclusion from 

 Steiner" s definition is that the ear is a brain. This conclu- 

 sion has not been drawn by Steiner himself, but is unavoid- 

 able. For, first, unilateral extirpation of the ear brings 

 about forced movements, and, secondly, the auditory nerve 

 is one of the higher sensory nerves. Steiner further points 

 out that bilateral destruction of an organ, the unilateral 

 destruction of which brings about circus motions, renders 

 impossible spontaneous progressive movements. Forced 

 movements can be brought about in the shark from the 

 medulla olihmt/ala, and here is located also, according to 

 Steiner, "the general center of locomotion" of this animal. 

 Steiner has himself shown, however, that a shark still moves 

 spontaneously after the loss of the entire medulla oblouyata. 1 

 This "center of locomotion" is said by Steiner to be 

 located in the medulla oblongata in the frog also, but 



l STEINER, Die Functionen des Cenlralnervensystems, Vol. II (1883), pp. 56 ff. 



