54 VIGNETTES FllOM INVISIBLE LIFE. 



seen half-a-dozen within one Yolvox sphere, and 

 watched their depredations for, however they 

 may get there, there they are, and must eat to 

 live ; and so the young, half -developed Yol voces 

 become their prey, and the whole globe is some- 

 times spoiled and rendered unproductive by these 

 little parasitic depredators. 



During the summer the Volvox ylobator continues 

 to propagate, as above described, by self-division or 

 multiplication ; but by the autumn two new kinds 

 of- cells make their appearance within the parent 

 globe. These are larger than the ordinary ones, and 

 do not divide or, rather, only one of them docs : 

 and tliis is in a totally dissimilar manner to the 

 usual plan. The new cell thus referred to is the 

 male or sperm cell, which, instead of dividing into 

 globes, simply develops itself into flat discs, and, 

 losing the green matter, is transformed into red or 

 yellow, and eventually appears as an elongated cell, 

 with a red eye-spot and two long cilia. The other of 

 the new cells is the female or germ cell, and does not 

 divide. It is at first pear-shaped, but finally becomes 

 globular and enveloped in a glutinous membrane. 

 As this operation becomes perfected, the sperm cells 



