SWIMMING AND CREEPING PROTOPLASTS. 



29 



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

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

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

 (fig. 7 2); and in others again, one or two pairs of long and infinitesimally thin 

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

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

 flagellum at one extremity (fig. 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 combined lashing and rotatory motion, and by 

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



Fig. 7.— swimming Protoplasm. 



1 Vaucheria; « CEdogonium; « Draparnaldia ; * Coleochcete; s and ? Botrydium; « Ulothrix; 8 Fucus; • Funaria; 

 10 Sphagnum; " Adiantum. 



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

 with the idea of fishes swimming with fins. 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 its motion may be compared to that of a 

 rifle-bullet, since in both cases the movement of translation takes place in the 

 direction of the axis round which the whole body spins. The movement in question 

 is not unlike 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 magnifies not only the moving body, but also the path 

 traversed; and when one contemplates a protoplast in motion, magnified, say, 

 three hundred 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 Vauche7'ia, 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. 



