1921] NATURAL SCIENCES OF PHILADELPHIA. 107 



certainly appear to be such; very often seem to start, not from a middle 

 region quite near the flagellum, but further away from the middle, 

 even from near the extreme border of the body, like an anterior 

 crown above the equatorial girdle of setae which we shall soon 

 speak of. But it only appears so, and in fact one can easily see, 

 on specimens favorablj^ oriented for such observations, that all the 

 threads of the crown have their origin in the immediate vicinity 

 of the central fiagellum. Sometimes, left and right of the flagellum 

 are seen two much smaller flagella, slowly undulating, and quite 

 independent from the big central one. These two small accessory 

 flagella, whose meaning has not yet been understood, seem to have 

 been a great puzzle for those few observers who noticed them; but 

 more protracted observations, with adequate material, would have 

 allowed of more certain conclusions. In fact, there are not always 

 two accessory flagella, but sometimes one or two, or more; or, on 

 a specimen where none was at first detected, suddenly there may 

 be seen to appear a crown of small flagella, which begin vibrat- 

 ing, and after a very short time slowly retract, getting thicker 

 the more they shorten — as if an axial thread were retracting into 

 the body while the enveloping protoplasm accumulated outside — 

 and finally collapsing each of them into a small roundish pearl. 

 But after a time, each of these little pearls rapidly lengthens again 

 into a long, fine thread, that becomes mixed among the other threads 

 or "pseudopodia" which had remained expanded and rigid. 



These observations, which have been repeated several times, 

 seem to justify the following statement: The threads which compose 

 the anterior crown are not pseudopodia, but flagella, which are 

 capable of changing rapidly in their appearance and function; 

 straight and rigid as a rule, they may for a time appear as flagella, 

 with slow, flexuous undulations. However, these accessory flagella 

 widely differ in their nature from the central one, which is a true 

 flagellum. They are also completely independent from each other, 

 one of them, for instance, is seen to vibrate while its next 

 neighbor remains stiff; or some developing into a vibrating crown 

 of flagella, while others persist in the shape of a rigid external crown 

 of pseudopodia (Plate V, fig. 2). 



As to the function of these special elements, for which we might 

 use the term "flagellopodia," in their rigid, pseudopodian state, 

 they must be considered as prehensile organs, stopping on their 

 way very small organisms or food particles and bringing them to- 

 wards the body; on two different occasions, for instance, I have seen 

 a small green particle caught by one of the rigid filaments, and the 

 thread curving over it, then slowly retracting and finally depositing 

 it on the surface of the body. This process is, however, not the 



