72 GENERAL HISTORY OF INFUSORIA. 



attached to the two sexual glands (Hydatina) . Dr. Ehren- 

 berg considers their function analagous to gills, and that 

 the tremulous motion is occasioned by the laminae, or 

 leaflets, which compose them. For the reception of water 

 into the interior of the body, for these organs to act upon, 

 there is an opening at the anterior part of the body, while 

 some species effect this purpose by means of one or two 

 spur-like processes or tubes, emanating from the neck (see 

 fig. 487), and by which water for the purpose of respiration 

 may be admitted or rejected. 



Section XXXIII. — Organs of Sensation and Nervous 



System, 



The Infusoria are not considered to possess a true 

 nervous system, but in many of the species having eyes 

 there appears one or two masses attached to them, which 

 Dr. E. thinks are similar to nervous ganglia and nervous 

 fibrillae. The eyes vary in number ; they are usually of a 

 red colour ; in some, they are placed upon a ganglion, and 

 are freely moveable beneath the transparent superficial 

 envelope of the body. 



Section XXXIV. — Geographical Distribution of Rota- 

 torial Infusoria, 



So far as observation extends, they do not appear to be 

 confined to any particular part of Europe, and they have 

 been found in the north of Africa, the north and w^est of 

 Asia, and in Carolina in America. 



