500 



It is clear from the above quotations that in all cilia or organs 

 resembling cilia in which on account of their size it has been hitherto 

 possible to observe any structure at all, they reveal themselves as 

 tubular extensions of the cell-substance enclosed by an elastic cuticula 

 or pellicle. 



Another point which is assumed by the theory is that by means 

 of movements of the cell-hyaloplasm which are similar in character to 

 those which produce amoeboid changes and like these are in all prob- 

 ability determined by local changes of surface tension, rhythmic 

 fluctuations of tension are produced in the interior of these tubular 

 extensions of the cell ; in other words that there is a rhythmic flow and 

 ebb of the cell-hyaloplasm into the bases of the cilia which is the ex- 

 pression of movements of the cell-protoplasm. Any such tubular cell- 

 processes which are subjected to rhythmic fluctuations of tension must 

 necessarily bend over in one direction if their pellicular covering is 

 constantly less extensible on one side; but if local changes in the 

 pellicle can still — as in the amoeboid cell — be effected at any part 

 of the cell-process, its movements, instead of being always in one plane 

 and direction, would be inconstant. In support of the assumption that 

 the movements of ordinary ciHa are accompanied and doubtless deter- 

 mined by movements of the cell-protoplasm, I am now in the position 

 to adduce the following observations which I will again give in Dr. 

 Puttee's words (p. 28): 



"Stuart (Ueber die Flimmerbewegung, Inaug.-Diss. Dorpat, 1867) 

 sah an den Flimmerzellen der Aeolidenlarven (Flabellina, Montagua, 

 Aeolis) ... bei abnehmender Tätigkeit der Zellen . . . wie die Kerne in 

 der Zelle auf- und abgeschoben wurden, eine Bewegung, die anscheinend 

 mit der Flimmerbewegung in Zusammenhang stand." 



"NUSSBAUM (Ein Beitrag zur Lehre von der Flimmerbeweguug, 

 Arch. f. mikrosk. Auat., Bd. 14, 1877) sah an der überlebenden Niere 

 von Selachiern, daß die Höhe der in den Harnkauälchen vorhandenen 

 Flimmerzellen isochron mit dem Schlag der zugehörigen 'Cilien (alle 

 Cilien einer Zelle schlagen hier synchron) ab- und zunahm, die Zellen 

 sich also kontrahierten und expandierten. Dies führte ihn zu der An- 

 nahme, daß Plasmabewegung in der Zelle die eigentliche Ursache der 

 Cilienbeweguug sein müsse". 



"Bonnet (Der Bau und die Zirkulationsverhältnisse der Acephalen- 

 kieme, Morphol. Jahrb., Bd. 3, 1877) sah an den Kiemen von Mytilus 

 edulis, wie sich das Zellenprotoplasma 'durch Formveränderung' ener- 

 gisch an den langsamen kräftigen Schlägen der aufsitzenden langen 

 Borsten beteiligte." 



