as Infusoria flagellata. 257 



which, although it has a pretty strong resemblance io Euglena, 

 heightened by the presence of a red eye-spot {s) , will be found 

 upon investigation to possess some additional and decidedly 

 different characters. In the first place, it has two vibrating 

 lashes {fl.,fl'^), which differ remarkably among themselves both 

 in position and character. One of them is always carried in 

 front, like a sort of proboscis (^); and in fact it seems to have 

 the office of such an organ, like that of an elephant, to feel and 

 to take hold of objects. I must confess that I was struck with 

 astonishment at the apparent intelligence with which the in- 

 fusorian extended, and twisted, and turned, and felt about with 

 this extraordinary organ. Never did an elephant seem to use 

 his trunk with more though tfulness. With like control did 

 the animal also use the other lash {fl^), always keeping it 

 turned back along the body, so that it formed a kind of move- 

 able keel when the little creature glided along in its watery 

 element, or was used to sway it from side to side, or oftentimes 

 to raise it u^ on its tail by forming a prop, as we see it in this 

 other figure (fig. 73). 



" The motory or propelling power, on the other liand, is re- 

 stricted, at least in the greatest measure, to another kind of 

 vibratile cilia. These are very short, and are crowded toge- 

 ther in great numbers (c/) in a broad furrow or depression (_/) 

 which extends over half the length of the body, along its in- 

 ferior middle line. When the body is turned over, and the 

 anterior end retracted and swelled out sideways, the fm-row 

 (fig. 73, /) becomes quite conspicuous, and the extent of the 

 group of minor cilia [cl] is easily ascertained. They are very 

 minute, and in constant motion, propelling the body backward 

 and forward, up and down, to the right or left, according as it 

 is steered by the trailing lash (/^) which extends along its 

 length. Thus it is that, although similar in form, a diversity 

 of fimctions is laid upon these three kinds of cilia that amounts 

 to the most marked specialization, through the simplest means 

 — in fact so simple that the eye cannot detect them in any 

 form besides that of proportion and position, and certainly not 

 in the intimate structure of these bodies. The whole body, 

 too, possesses a flexibility and extensibility scarcely inferior to 

 its cilia : at one moment it is darting through the water, sharp 

 as a lance at both ends ; and at the next it is as round as a ball, 

 or worming its way through tortuous passages with every 

 possible degree of flexure short of actually tying itself into a 

 knot." 



It would be difficult to say now whether Heteromasttx be- 

 longs to the Flagellata rather than to the Ciliata, or vice versa. 

 The structure, position, and peculiar mode of action of its fla- 



