130 



A remarkable sight to watch siich a flagellated chamber! At 

 first one sees only a round hole into which, so to say, the water 

 runs in from all sides in incessant current, like a round cas- 

 cade (the water disappearing in the middle). 



Of course, this is only optical delusion. The current of water 

 itself cannot be observed, and what one took for the undulating 

 streamlets are simply the (spiral-)waves of the flagella, that run 

 on from all sides of the chamber to the centre. For the choano- 

 cytes are, with their base, attached to the inside of the wall of 

 a globular space (the chamber), so the flagella are all directed 

 towards the centre (Fig. 55). The collars will be treated lateron. 

 Examining now the flagella very accuratelg, one immediately 

 recognizes the fagellar tnotion^ that we have got to knoiv above as 

 normal in the isolated choanocytes {eg. Fig. 56a)] hut this one here 

 is much stronger! The (spiral-jiraves are running on very clearly 

 in rapid succession from the base towards the top of the flagellum ; 

 their amplitude is very small, still smaller than Fig. 56« shows; 

 sometimes the flagellum is almost stretched ; another time it seems 

 as if there are some smaller waves superposed on the larger ones, 

 which is certainly possible. 



An accurate illustration of such a strongly acting flagellated 

 chamber is given in Fig. 59, drawn from nature. Beside the (ge- 

 nerally occurring) very rapid spiral- or undulating-motion some 

 flagella of a chamber may show a somewhat slower one with a 

 larger amplitude, in the way as shown in Fig. 56 b. Probably, 

 this last phase is inserted now and then, as a rest-period, be- 

 tween the normal, quick undulatings ; I at least saw it sometimes 

 pass into the rapid one. 



For hours one may observe the movements ; one n e v e r sees 

 any other than those, mentioned here : the quick (spiral-)waves 

 with now and then a slow one between. I have observed them 

 ropeatodly in numerous diiferent preparations, in the course of 

 scveral years (1915 — '16 — '17); always with the same result. 

 Also, Professor Yosmaer and Professor Pekelharing — I am 

 very glad to mention — have enabled me to demonstrate to 

 them, in my living preparations, the flagellar motion of the in- 



