INFUSORIA 



describe its ordinary form as spindle-shaped, with a pointed 

 tail, and a blunt, rounded head; but it is remarkable for 

 the variableness of its shape. It is capable of assuming 

 an appearance very diverse from what it had half a minute 

 before, so that you would hardly identify it, if you were 

 not watching its evolutions. Whether this ability to prove 

 an alias be at all dependent on the remarkable clear-headed- 

 ness of the subject, I leave for you who are skilled in meta- 

 physics to determine. Away they go tumbling over and 

 over, revolving on the long axis as they proceed, which 

 they do not very rapidly, with the blunt extremity for- 

 ward. 



Here is another form, a little larger than the former, 

 but much more slender; yet from the slowness and steadi- 

 ness of its movement more easy of observation. It is 

 named E. acus, or "the Needle Euglena." This is an 

 animalcule of great elegance and brilliance; its sparkling 

 green hue, with colorless extremities, and its rich pale 

 crimson eye, are very beautiful. It commonly swims ex- 

 tended, with a slow gliding motion, turning round on its 

 long axis as it proceeds, as may be distinctly seen by the 

 rotation of certain clear oblong substances in its body. 

 These then are seen not in the interior, but near the sur- 

 face, as they would appear if imbedded in the flesh around 

 a hollow centre. The interior is* probably not hollow, but 

 occupied with pellucid sarcode. These were assumed by 

 Bhrenberg, but on no adequate grounds, to be organs con- 

 nected with reproduction. They vary in number in differ- 

 ent individuals, and those which contain the greatest num- 

 ber are thereby more swollen. They appear to be separated 

 into two series, one anterior, the other posterior. The ani- 

 mal is capable of bending its head and body in various 



