-42- 



animal neatly avoiding the obstacle and migrating off in the 

 direction indicated by the upper arrow. This is a very interest- 

 ing reaction and has been made the subject of careful study below 

 in an effort to discover the factors concerned in this breaking up 

 of the coordinated impulse* 



Mangold (1908) has described an observation in the slen- 

 der armed Luidia ciliaris in which the animal was seen to have an 

 arm bent so that coordinated tube feet, all extending in the same 

 direction, were some extended out to the right of the ray, some 

 parallel wi th the ray and some to the left of the ray. 



If we are to explain this very puzzling behavior from a 

 physiological standpoint we can not merely point out its adaptive 

 or regulatory value, we must attempt an analysis of iti mechanism. 

 It is futile also, to conjure up a complex "center" in the nervous 

 system which acts as eoordinating mechanism or presiding regulator, 

 orienting the tube feet of various parts of the body in such a man- 

 ner as to best accomplish the act of the moment. Ste iner (18 98^ 

 hypothesizes a "righting center" and Preyer (1886) "centers" for 

 various activities* There is no structural basis for such an assump- 

 tion # and it is not in accord with observations on the behavior of 



# Spix, (1809) described a nervous system for the starfish that 

 would satisfy such an assumption. Unfortunately, ,however, it proved 

 to be the system of gastric and hepatic mesenteris filaments. 



Acceding to Baudelot (1872) who gives an historical resume of 

 the earlier morphological literature the subject became so oontrover- 

 sal that A. H. Quatrefages (1842) made the statement freely trans- 

 la tad as follows. "Naturalists of great merit have come to such 

 diverse conclusions as to the significance of the various systems 

 of (Bchinoderm) organs described as nervous in function that I have 

 decided to remain in this regard in a state of philosophical doubt." 



