6 The Mycetozoa^ and 



stances, i.e., with sufficient moisture and warmth, small 

 translucent bits of naked protoplasm will be seen to 

 emerge from them, leaving a mere shell behind them ; 

 these bits of protoplasm have a movement of their 

 own in the water, and can be seen both to shake 

 themselves, and to move forwards ; they push out a part of 

 their protoplasm as a whip or flagellum at one end of the 

 body, swimming with this in front of them, the whip 

 having a sort of lashing movement. Fig. 3 exhibits 

 some of these bits of protoplasm. Their motions are 

 particularly amusing to watch; they swim, they wriggle, 

 they revolve, they shake themselves, they are full of 

 life and motion ; they seem at once wilful and purposeless ; 

 they gambol with one another, and their frolics remind 

 one of young lambs in spring. They are capable not 

 only of motion but of digestion, and of the capture of food 

 in a manner to be hereafter described. These little pieces 

 of protoplasm bear several names, and as the variety of 

 phraseology is apt to puzzle students, we pause to say 

 that they are called sometimes swarm spores, or swarm 

 cells, sometimes zoospores, and as individual pieces of 

 protoplasm they are sometimes called protoplasts. The 

 spore of a moss, or of a fern, is a small structure, endowed 

 with no power of motion ; these swarm spores, as we have 

 seen, have a power of motion ; the spore of the moss, or 

 the fern, is capable by itself of reproducing the plant from 

 which it has come, but these swarm spores are only repro- 

 ductive after fusion with others, as we shall hereafter see. 

 The name swarm cell is likely to mislead, because the 



