CYCLOSIS IN DESMIDIACE.E. 



•201 



and these streams detach and carry with them, from time to time, 

 little oval or globular bodies (a, b) which are put-forth from it, and 

 are carried by the course of the flow to the chambers at the extre- 

 mities, where they join a crowd of similar bodies. In each of 

 these chambers (b), a current may be seen from the somewhat 

 abrupt termination of the Endochrome, towards the obtuse end of 

 the cell (as indicated by the interior arrows) ; and the globules it 



Fig. 111. 



Circulation in Closterium lunula: — a, frond showing centra 

 separation at a, in which large globules, b, are not seen ; — b, one 

 extremity enlarged, showing at a the appearance of a double row 

 of cilia, at h the internal current, and at c the external current ; 

 — c, external jet produced by pressure on the frond (?) ; — d, frond 

 in a state of self-division. 



contains are kept in a sort of twisting movement on the inner side 

 (a) of the primordial utricle. Other currents are seen externally 

 to it, which form three or four distinct courses of globules, passing 

 towards and away from c (as indicated by the outer arrows), where 

 they seem to encounter a fluid jetted towards them as if through an 

 aperture in the primordial utricle at the apex of the chamber ; and 

 here some communication between the inner and the outer currents 

 appears to take place. * This circulation is by no means peculiar 



* See Mr. S. G. Osborne's communications to the "Quart. Journ. of 

 Microsc. Sci.," Vol. ii. (1854), p. 234, and Vol. iii. (1855), p. 54.— Although 

 the Circulation is an unquestionable fact, yet I have no hesitation in 

 regarding the appearance of ciliary action as an optical illusion due to 

 the play of the peculiar light employed among the moving particles of 

 the fluid; the appearance which has been thus interpreted being pro- 

 ducible at will (as Mr. Wenham has shown in the same journal, Vol. iv. 

 185G, p. 158) by a particular adjustment of the illumination, but being 



