DIVISION OP COLLAR-CELLS OF CLATHRINA CORIACEA. 635 



conclusions being drawn with regard to the homologies of the 

 flagellar apparatus of trypanosomes. It is, of course, possible 

 that the conclusions drawn from the one do not strictly apply 

 to the other, and it is certainly very desirable that these 

 points should be studied in flagellates generally, and in forms 

 allied to trypanosomes particularly, more than has been 

 done at pi*esent. On the other hand a collar-cell, although it 

 forms part of the epithelium of a sponge, is as much a 

 flagellate organism in all points of structure and function 

 as any free-living flagellate; and the study of cytology tends 

 rather to demonstrate the essentially uniform nature of 

 permanent cell-structures throughout the whole range ot 

 living organisms, whether animal or vegetable. 



Lister Institute, Chelsea, S.W. 

 April 26th, 1910. 



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