236 H. P. KJERSKOG AGERSBORG. 



external conditions. The lack of oxygen, or the insufficient 

 amount of it causes, as demonstrated by Loeb (6) and others, 

 ". . . at first molecular, and later morphological changes in the 

 cells, which in turn are the cause of the supension of life-phe- 

 nomenon." No apparent morphological changes were observed 

 on the star from the lack of oxygen, but the unbalanced behavior 

 seems to indicate some changes to have taken place. The effect 

 of the stimuli received from the righting impulse, whether it be 

 a normal or an abnormal individual, is to move away from the 

 place of disturbance. (Fig. 3, Plate I). 



Such definite movements tend to show that Pycnopodia has 

 some established habits. In this respect it is indeed very much 

 different from the common starfish, e. g., Asterias forbesi and A. 

 vtdgaris, which, according to Dr. Coe (2), "Do the same thing, 

 under the same conditions, in a number of different ways, and 

 never do the same thing twice in exactly the same way." 



Jennings (4) also makes a statement similar to that of Dr. Coe, 

 when he says: 'The starfish Asterias firreri) is not hampered 

 by any consideration of anterior or posterior; it may move with 

 any of its rays in the lead, or with any interradius in advance, 

 or indeed in any intermediate direction, so that its possibilities 

 as to direction of locomotion are really unlimited. In the same 

 way, it may right itself in an indefinite number of different ways." 

 Pycnopodia, however, has already formed certain definite modes 

 of behavior. Part of these is indicated by its righting reactions. 

 The speed of righting, as seen below, is not improved by repeti- 

 tion, but the method of righting indicates clearly that it possesses 

 a more definite control of its muscles, or has a more definite 

 method of righting itself than has the common starfish. In 

 regard to habit formation the result is negative. 



Jennings (4), in describing the righting reactions of the common 

 starfish, says: "After repeated experiences by a given individual, 

 there was no improvement in the performance of this reaction, 

 either in the time taken, or in the movements employed in 

 accomplishing the righting." 



The first eleven trials show uniformity in speed of righting 

 reaction; the first three show the same speed. Then there is a 

 very rapid turn, taking only half the time of one of the previous 



