FLAGELLATE INFUSORIA AND ALLLED ORGANISMS. 73 



with fluid makes its appearance beneath the upper surface 

 of the body at the spot where the last vacuole disappeared 

 (fig. 7 c, v) ; this space, so far as can be determined, is 

 formed by the flowing together of several smaller vacuoles. 

 Shortly before the systole the space rounds itself into a 

 vacuole. 



The author has, unfortunately, failed to find the condition 

 of division, and so has not been in a position to confirm 

 Clark's interesting observations on this point, which are 

 shortly as follows : — The division occurs longitudinally, and 

 so is in conformity with the general rule amongst the Flagel- 

 lata. The organisms next become globular, and the flagel- 

 lum becomes shorter and shorter, till it is finally entirely 

 withdrawn into the protoplasm. Then begins the peculiar 

 division of the body of the organism in the neighbourhood 

 of the flagellum, from which point it gradually proceeds 

 backwards ; finally, the collar is drawn into the division, 

 and is gradually cut through from the base to the apex. In 

 the meanwhile, a flagellum, which is at first small, but 

 which gradually increases as the process of division proceeds, 

 is budded out from the anterior end of each of the products 

 of the fission. The posterior thread-like elongation of the 

 body, which attaches the organism to the common stalk of 

 the colony, also undergoes division, until "finally the two 

 products of the fission become completely separated. 



The author has observed forms which were surrounded by 

 a delicate viscid case (fig. 7 b), and also others whose bodies 

 were covered with Bacteria (fig. 7 e). 



The average size, not reckoning the collar, was 0*012 mm. 

 The organisms have been found very frequently upon Algae 

 and so forth, upon the stems of A7itophysa vegetans, and once 

 upon colonies of Volvox dioicus, Cohn. They withstand a 

 considerable degree of foulness in the water where they 

 occur. 



Salpingoeca, Clark (' Ann. and Mag. Nat. Hist.,' 4th ser., 

 vol. i, p. 199). 



This genus difiers from the foregoing in the fact that the 

 animals live in transparent cups or flask-like shells ; they are 

 solitary, and not colony-forming as far as they have yet been 

 observed; their method of reproduction is unknown. 



Salpingoeca gracilis, Clark? (op. cit., p. 199, pi. vi, 

 figs. 38 and 39). 



This organism (Plate vi, fig. 8) resembles Codosiga, 

 but inhabits an elongated case, which has sometimes 



