Movement and Problem Solving in Ophiura 207 



Thus, in June of the present year, more than half of the animals 

 I studied were very active and quickly responsive to stimuli 

 during sometime of my acquaintance with them, but by August 

 the whole race had changed. Perfectly fresh material brought 

 into the laboratory in excellent condition and kept in large tanks 

 of running sea-water, was so sluggish that I was forced to give up 

 the experiments which I had planned for that month. None of 

 the stimuli employed in June elicited reaction, and acids suffi- 

 ciently concentrated to attack the skeleton, as well as the electrical 

 current, resulted in nothing but a few spasmodic contractions with 

 no attempt at progression or escape. What the reason for this 

 change was is not certain. A sluggish individual almost always 

 has very large bursal openings; in fact, it is possible to predict 

 with considerable certainty the behavior of an individual by 

 examining its ventral surface. The enlarged bursal openings 

 may be consequences of the spawning process, and the periodic 

 change of behavior of the breeding activities. O. brevispina 

 begins breeding in June and ends in August. Late in June many 

 individuals have spawned, and many have the enlarged bursal open- 

 ings; by the middle of August all have spawned (Grave '00) and 

 most of the individuals have the enlarged bursal openings. As 

 the genital ducts lead into the bursae — which in some species are 

 used as brood-pouches — their enlargement may very well be 

 due to sexual activity, which is a drain upon the animals, and 

 undoubtedly leaves them in a state of physiological depression. 

 If this view is correct, the enlarged bursal openings are the indices 

 of a lethargic state following the breeding season. 



Rapidity and sluggishness of movement have consequences of 

 great importance in problem solving. Sluggish animals not only 

 make fewer movements and take more time to perform them than 

 active individuals, but they use in general fewer arms; their move- 

 ments are less varied, and the arms very rarely come into contact 

 with one another or cross. All this is very different with active 

 individuals; their movements are quick and varied; they use 

 relatively more arms, often move these through greater arcs than 

 the sluggish animals; and, in addition, the arms touch and cross 

 with great frequency. How "contacts" and "crosses" are related 



