152 ROMANCE OF LOW LIFE AMONGST PLANTS. 



mass. The young swarmers, for a short time after 

 they issue, have only a narrow yellow rim round a 

 dark red middle. During the two or three days' 

 period of movement and growth of these swarming 

 cells— in which they attain to four times the original 

 size, changing their ovate to a pear-shaped form,— 

 important changes take place in their contents. The 

 red colour becomes more concentrated into the 

 middle of the cell, so that a sharply defined red 

 nucleus is formed, with a lighter space in the interior, 

 corresponding to the nuclear vesicle, around which 

 the red colouring matter forms a covering more or 

 less complete. The rest of the cell contents have 

 become a brilliant green, and in them the starch 

 granules, with smaller green granules, are visible. 

 The ciliated point of the cell, often drawn out like 

 a beak, is colourless. This first moving generation 

 is succeeded by a number of similar active genera- 

 tions, populating the water for some weeks, often 

 giving it a bright green colour, until, at length, uni- 

 versal rest recommences, and the cells sink to the 

 bottom, or attach themselves elsewhere. The transi- 

 tion from one active generation to another passes 

 through a resting generation of extremely short dura- 

 tion. The full-grown swarming cells finally come to 

 rest within their wide envelope, and almost simul- 

 taneously divide into two cells, which, without 

 becoming active, divide again into two cells. Thus 

 within the parent envelope four daughter-cells are 

 produced, which begin to move soon after they are 

 completely formed, and, rupturing the thin envelope, 

 make their escape. The whole of this process is very 



