INFUSOKIA. 



Ill 



inconveniences of a maximum of spherical aberration and a total want 

 of stability, were only fit for use in the hands of Leuwenhoek himself, 

 who had acquired, in his labour of twenty years, habits of observation 

 which compensated, in great part, for the want of perfection in his 

 instruments." 



The Euglenise are infusoria usually coloured green or red. Their 

 form is very variable. They are oblong or fusiform in shape, swelling 

 at the middle during action, and contracted or bowl-shaped in repose, 

 or after death. They are furnished with the usual whip-shaped 

 filament, which issues from an opening in front, and from one or 

 many reddish points irregularly placed anteriorly. 



Euglenia viridis (Fig. 36) is the most common species, and, per- 

 haps, the most widely diffused of all the Infusoria. It is this animalcule 

 which habitually covers stag- 

 nant pools with its floating sur- 

 face of green, and which forms, 

 on the surface of marshy waters, 

 the shining pellicle so strongly 

 coloured, which, collected upon 

 paper, so long preserves its bril- 

 liant tint. 



The Euglenia sanguinea, at 

 first green, becomes subsequently 

 of a blood colour. It has often 

 been met with by microscopists. 

 Ehrenberg, who first described 

 it, attributes to its great abun- 

 dance the red colour of some 

 stagnant waters. Its presence 

 explains the pretended miracle 

 of water changing into blood, 

 which was frequently invoked 

 by the Egyptian priests. 



s 



Fig. 36. Euglenia viridis (Ehr.), magnified 350 times. 



CILIATE INFUSORIA. 



Let us now take a glance at some of the more remarkable species 

 of Ciliate Infusoria. TLe bodies of these creatures are all more or 

 less translucent. They have not substance enough, in fact, to reach a 



