SWIMMING AND CREEPING PKUTUl'LA.STS. Ct> 



project from the surface of its body. In some instances tlie whole surface is thicklj- 

 covered with short cilia, as in Vaucheria (tig. 7 '); in others the cilia form a close 

 ring behind the conical or beak-like end of the pear-shaped body, as in (Edogoniuin 

 (fig. 7-): and in others again, one or two pairs of long and infinitesinially thin 

 threads, like tlie antennaj of a butterfly, proceed from some spot, generally the 

 narrow end (tig. 7 ^ and 7 ^). Many forms are provided with a single long lash or 

 flagellum at one extremity (tig. 7''), and yet others are spirally wound and are 

 beset with cilia, thus presenting a bristly or hirsute appearance (fig. 7 "). 



These ciliary processes have a coiiiläned la.shing and rotatory motion, and by 

 their means the protoplasts swim about in water. In many cases, however, swim- 



Fig. 7. — Swiniiniiiy I'rotophism. 



> Vauchei-ia; - (EdogonUtm : ^ Drnpnnmldin : ' Colcochrete : = and ' Bntnjdium; ' Ulvlhiix; » Fiiciis; ^ t'liiiai!« ; 



i'^ Sphaf/imm; " Adiantutn. 



ming is hardly an appropriate expression: certainly not if one associates the term 

 with the idea of fishes swimming with tins. In point of fact there is, associated 

 with progression in a particular direction, a continuous rotation of the protoplast 

 round its longer axis, and on this account the motion has been compared to that 

 of a bullet, though even this comparison is not accurate, seeing that the motion 

 of translation in swarming pi'otoplasts takes place in the direction of the axis 

 round which the whole body spins. The movement in question is best likened 

 to the boring of one body inside another; according to this, the soft protoplasts 

 bore through the yielding water, and by this action make onward progress. 



The microscope magnities not only the moving body, but also the path 

 traversed; and when one contemplates a protoplast in motion, magnitied, saJ^ 

 three hundi-ed times, its speed appears to be three hundred times as fast as it 

 really is. As a matter of fact, the motion of protoplasts is rather slow. The 

 swarm-spores of Vaucheria, described above, which traverse a distance of 17 

 millimeters in a minute are amongst the fastest. The majority accomplish an 

 advance of not more than 5 m.m., and many only 1 m.m. per minute. 



