The Behavior of Loxophyllum 417 



that these movements are gradually working the part into the 

 form of the whole. In the regeneration of the posterior half, for 

 instance, one may see the oral margin extending and extending, 

 growing a little longer with successive stretchings, until it curves 

 about the anterior end of the body, and its striations are bent 

 around so as to give the characteristic appearance of that region 

 of the normal animal. The same kind of action is apparently 

 instrumental in producing the same kind of form. 



But precisely what is the relation of the movements of the organ- 

 ism to its regeneration does not, however, lie on the surface. It 

 seems evident that the movements have an important part in 

 shaping the general outline of the body. But are they the funda- 

 mental causes of this change of shape, or agencies which merely 

 assist or accelerate the action of other formative factors .^ The 

 experiments performed, while they indicate the importance of 

 behavior in regeneration, show, I believe, that this factor is of a 

 secondary or subordinate nature. It will be instructive to con- 

 sider the course of regeneration in those experiments in which 

 most or all of the oral margin was removed. Here regeneration 

 was forced to follow a very different method from that adopted 

 in the cases first described where a part of the oral margin was 

 stretched out into the whole. The new margin had to be formed 

 entirely de novo. There were involved the thinning out and 

 clearing up of the oral side, the differentiation of new contractile 

 threads, new trichocysts, new cilia, a complicated ordering of 

 newly differentiating structures. The gross movements of the 

 body could have had very little to do with all this. Until these 

 differentiations were made the movements of this side of the body 

 were not of the usual kind. Commonly the oral side extends and 

 contracts more than the aboral, but when the marginal elements 

 of this side were removed the opposite side was the more active. 

 The oral side did not extend so rapidly as the aboral until the 

 structures characteristic of the oral margin were established. 



If in the experiments first described the general form of the 

 body seemed to be produced by the characteristic behavior of the 

 animal, the characteristic behavior in this case had to wait until 

 its structural basis was established by comparatively slow differ- 



