694 



EAYMoND I'EAKL. 



the Infusoria, and to find the same thing in a multicellular 

 oro-anism is a matter of considerable interest. It is out- 

 side the sco])e of the present ])a])er to discuss tlie relation 

 of this result to current theories of electrotaxis, as I hope 

 to be able to do in a later paper, but it may be said that 

 this furnishes another strong- piece of evidence that in the 

 case of these lower organisms the current does not cause the 

 observed reactions in any way comparable to that in which a 

 mechanical stimulus causes a reaction, i. e. by furnishing a 

 certain "sensation." On the contrary, the current acts as 

 a physical force on a structure organised in a certain way. 

 Experiments on the electrotactic reaction of cut pieces of 



4- 





Fig. 48. — Diagrain slinwinj? the electrolactic reaction of the rhabdocele, 

 Stcnostoma leucops, O. Schm. 



])l!Uiarians have been tried in considerable numbers, but with, 

 on the whole, unsatisfactoiy results. Anterior pieces result- 

 ing from transverse cuts are the only ones from which I have 

 been able to obtain any constant results. Such pieces react 

 like the normal uiiinKil in every way. Posterior pieces from 

 transvei'se cuts show the contractions on the anode side and 

 ends in a slight degree, but there is no constant production 

 of orientation. Specimens slit longitudinally in the middle 

 line fr()ni tlie posterior end nearly to the liead iH'act 

 essentially like a normal specimen, although nuicli more 

 weakly. I have observed in one case fairly precise orienta- 

 tions of such a s[)eciiiien. I'^roiii s])ecimens slit h)ngitii(linally 



