632 



STUDIES IN GENERAL PHYSIOLOGY 



FIG. 155 



in contact with a solid body, while, in an Antennularia a 

 change in the position of the polyp toward the vertical 

 suffices to bring about this result. 1 



While these processes are going on, the material of the stem 

 begins to creep or grow out of the original periderm. It 

 , seems to me worth while to 



call the attention of the 

 reader to the fact that in this 

 case the process of groidh is 

 identical with the process of 

 progressive motion of a pro- 

 toplasmic mass. In plants 

 growth occurs mostly near the 

 apex of an organ. If we look 

 at the increase in size of the 



stolon from the point of view of growth we notice that its growing 

 point is near the apex, just as in plants. But if we look at it 

 from the point of view of progressive amoeboid motion we notice 

 that only the foremost point creeps and that the rest of the pro- 

 toplasm is pulled out more passively. That the protoplasm 

 of the stem is under a strain will be seen by a glance at 

 Figs. 152, 153, 154, and 156. The coenosarc or protoplasm 

 lies in the periderm in the same way as a stretched rubber 

 thread would lie. Wherever the periderm is bent the proto- 

 plasm touches it on the concave side. It follows as nearly 

 as possible the shortest line in the periderm. It is possible 

 that the strain under which the cosnosarc is kept causes the 

 protoplasm to flow in the direction of the strain toward the 

 tip of the stolon. Botanists are inclined toward an ex- 

 clusively osmotic conception of the process of growth. I 

 have come more and more to the conclusion that the osmotic 

 theory of growth is not in harmony with the phenomena 



1 In former papers I have described the fact that in Eudendrium the polyps 

 are thrown off when the stems are put into small dishes. Such phenomena may 

 occur also in Campanularia, but this was not the case here. [1903 J 



