DYNAMICS OF REGENERATIVE PROCESSES 



219 



case of a piece from the body wall of an Actinian which has no digestive 

 organs, the material of the new tentacle can come only from one of two 

 sources, viz. from the chlorophyll (or parasitic algae?) which are con- 

 tained in the ectoderm, or through a hydrolysis of material contained in 

 the cells of the Actinian itself ; this latter case would be comparable to 

 Miescher's observation of the growth of the sexual glands at the expense 

 of muscular tissue. In the case of the polyp formation in Tubularia, 

 the transformation of the material of the stem into the polyp can be 

 directly observed (Bickford, Driesch, and others). It is even doubtful in 

 these cases whether a hydrolysis is necessary in any considerable amount, 

 and it looks as if the tissues could be utihzed directly for the formation 

 of the polyp ; some hydrolysis may however occur. In the above-men- 

 tioned case of the transformation of a branch of Antennularia into a 

 root, the polyps that were on that branch first disappear. I cannot 

 make any definite statement as regards their fate, but it is not impossible 

 that the material of the polyps is used for the formation of the new roots. 

 I have observed more closely the transformation of an organ into 

 more undifferentiated material in Campanularia, Fig. 62, a hydroid.* 

 This organism shows 

 a remarkable stereo- 

 tropism. Its stolons 

 attach themselves to 

 soUd bodies, and the 

 stems appear on the 

 side of the stolon 

 exactly opposite the 

 point or area of con- 

 tact with the solid 

 body. The stems 

 grow, moreover, ex- 

 actly at right angles 

 to the solid surface 

 element to which the 

 stolon is attached. 

 If such a stem be 

 cut and put into a 

 watch glass with sea 



water, it can be observed that those polyps which do not fall off go 

 through a series of changes which make it appear as if the differ- 

 entiated material of the polyp were transformed into undifferentiated 

 material. ' The tentacles are first put together Uke the hairs of a 



* Loeb, Am. Jour. Physiology, Vol. 4, p. 60, 1900. 



Fig. 62. 



