708 



of the ciliary raoveraeiit. ot the environment could readih' be ima- 

 gined to influence the movement of the cells of the turned implant- 

 ate, considering our view of the conduction of the stimulus in the 

 ciliated epithelium. 



Classic experiments have in this tield been carried out by Verwokn '). 

 They tended tu show tiiat every ciliated cell, nay, every separate 

 ciliuin has a movement of its own. However, for tiie regular action of 

 the entire epithelium, in which not a single ciliated cell begins to 

 move before its predecessor ("metachronic" ciliary movement aflei- 

 Verworn), an interconnection of all those cells is indispensable. If 

 one ot the anterior vibrating elements (ciliated plates on the ribs of 

 Beroë. Inquiry by Verworn') is checked in its nioveuient, all tlie 

 rest will stop \ibrating. If an incision is made, the part distad of 

 the incision will nol vibrate any longer witii the same rhythm as 

 the part proximad of it. The first element posterior to the incision 

 now marks the rhythm, which is taken over by the succeeding vibra- 

 ting elements. 



We cannot but ass e thai a conduction of the stimulus must 



take place in the ciliated epithelium (in the free border of the cell), 

 and that all the ciliated cells are interconnected (literature Ehhard). 

 If this is the case, we might imagine the direction of the ciliary 

 movement to reverse in the rotated patches of ciliated epithelium 

 that have coalesced with the environment, since the conduction of 

 the stimulus in these patches will now be just the reverse of the 

 normal conduction. 



But the fact that the healing of the patches of the oral mucous 

 membrane was rather tardy and was attended with inflammation of 

 the bordei-s of the wound, justifies our doubt as to the existence of 

 any normal organic connection between implanlate and surroundings. 



With a different object in view I have been working on larvae 

 of Rana esculenta and of Triton alpestris, in the Zoological Institute 

 of the Freiburg university (Director Prof. Dr. H. Spemann). Ectoderm 

 patches were detached and after a rotation of 90° or 180° they 

 were allowed to coalesce again. As the larval epidermis contains 

 ciliated cells and exhibits a very regular ciliary movement (vide 

 AssHETON ')), 1 was now in a position to study the efU'ect of these 

 rotations on the ciliary movement. 



Beforehand it should be stated that the rotated patches of ectoderm 

 in young amphibian larvae coalesce in. a wonderfully short time 



n M. Verworn. Pflüger's Arch. f. d. ges. Phys. Bnd. 48. 1890. 



") K. AssHKTON. Quarterly Journ. of microüc. Science. New Series. Vol. 38. 1896. 



