INFUSORIA. 145 



so that the matter of color does not affect anything in this com- 

 parison. So far, then, the argument holds good for their close 

 relationship ; but when I assure you that the Euglena as fig- 

 ured here is only one of the many forms which the same 

 individual may assume from moment to moment, and that 

 you may see it change before your eyes, almost as quick as 

 thought, from this elongate figure (fig. 86) to one like this 

 pear-shaped infusorian (fig. 88, B), and that in the next sec- 

 ond it is stretched out and pointed at each end like a spindle, 

 as in this figure, (fig. 88, A,) and, in the midst of these vari- 

 ous elongations and contractions, exhibits an extreme de- 

 gree of flexibility, at times fairly doubling itself up end to 

 end, as you would fold a strip of india - rubber, you cannot 

 fail to- appreciate the marked diversity of character between 

 the two objects in question. How far this distinction goes, 

 we will not stop to discuss until we have seen these other kinds 

 of infusorians. The separation apparently grows wider yet 

 when we learn that Euglena takes in food in the form of solid 

 particles, and stores them away in globular cavities, sometimes 

 called the digestive vacuoles. 



There is still another peculiarity among these spore -like 

 Infusoria which does not find its parallel in the sea -weeds. 

 I refer to the contractile vesicle. I was fortunate in obtaining 

 another infusorian, Chlamidomonas, (fig. 87,) 

 which resembled the spores of some of the sea- 

 weeds so closely, not only in form and actions, 

 but also in size, which in the doubly ciliated 

 spores is very minute, that, were it not for one 



almost inconspicuous character, I should certainly 



, f Fig- 37. 



have taken it lor the colorless spore 01 some 

 water-weed, or of something like the snow-plant. That charac- 

 ter was exemplified in its double contractile vesicle (c). These 

 vesicles appeared and disappeared alternately, or sometimes both 

 together, with considerable rapidity, and yet, notwithstanding 



Fig. 87. Chlamidomonas palUda, n. sp. 500 diam. c, the pair of contrac- 

 tile vesicles ; I, the vibratory lashes. Original. 

 10 



