152 Vniversitij of California Publications in Zoology. [^'ol. 4 



attached. Now one of the other arms was placed on the tube and 

 it was thus held down against the bottom, Avhile the stump of the 

 arm was pulled out of it. 



These interesting facts have been called in question by Loeb. 

 He says "I have repeated the experiment on these animals and 

 found that the Ophiuris pays no attention to the rubber tube. 

 The animal of course loses it after a time unless it fits too closely, 

 but it is always purely a matter of chance" (Loeb, 1900, p. 65). 

 It is, therefore, proper to point out that Preyer's facts have 

 been essentially confirmed by later investigators. V. l>xkiill 

 (1904) gives a series of kinetographic photographs of the brittle 

 star while engaged with the adjacent rays in the scratching 

 movements ("Kratzbewegungen") by which the tube was finally 

 removed. Glaser (1907) described similar actions. I performed 

 the same experiment with a species of Ophiuris (0. panamoisis 

 Liitken) Math similar results. I observed in the course of my 

 experiments all but one of the five different methods of getting 

 rid of the tube which Preyer described. In one case the two 

 adjacent arms were placed against the tube in the way figured 

 by Preyer, pushed out in such a way as tended to remove the 

 tube; drawn back and again placed against the tube and pushed 

 outward, and this was repeated six times in succession. 



Of course not all the specimens on which this experiment is 

 tried proceed in the same way in removing the tube, nor does; 

 the same one behave in the same way at all times ; this was 

 specially emphasized by Preyer. The denial of such observations 

 is likely to come from investigators who are fully convinced of 

 the truth of the ancient dogma that the behavior of the lower 

 animals is stereotyped and invariable. Holding to this view, 

 one or two 'crucial experiments' are deemed all that is nec- 

 essary to set the matter at rest. When the established truth that 

 the behavior of the lower organisms is specially characterized by 

 variability and changeability is generally recognized, we shall 

 have fewer dogmatic statements as to the precise limitations of 

 these animals and as to what they are forced to do under certain 

 outward conditions. 



Why did Preyer call this behavior "intelligent"? In the 

 case of such thorough workers as Preyer, we are likely to gain. 



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