543 INFUSORIAL ANIMALCULES 



spiral turns in its passage. He does not affirm that he has ever 

 distinctly seen food passing along this narrow intestine ; or that 

 he has been able to trace the walls of the globular stomachs, any 

 more than of this alimentary tube, when they are not filled out 

 with colouring particles. 



1206. The views of Ehrenberg were never by any means 

 universally received amongst Naturalists ; and it is now admitted 

 by all who have paid attention to the structure and habits of 

 the Infusoria, that they are very erroneous. A kind of circula- 

 tion is seen to be performed by the globular masses already men- 

 tioned, as if they floated loosely in the cavity of the Animalcule, 

 and did not form part of the supposed alimentary canal. And it has 

 been found that, when a small quantity of an alkaline solution is 

 allowed to touch their bodies, they burst, and discharge these 

 globules, which seem to have been imbedded in a soft gelatinous 

 substance. 



1207. According to the views which have been lately put 

 forward with considerable appearance of truth with regard to 

 the organisation of the Infusoria, these microscopic creatures are 

 neither to be regarded as simple cells, nor as endowed with a 

 complicated system of alimentary and other organs, such as were 

 ascribed to them by Ehrenberg and his followers. They ap- 

 pear to consist of a gelatinous envelope of greater or less thick- 

 ness, containing in its substance the nucleus and contractile 

 vesicle already mentioned ( 1 197), and enclosing a large cavity, 

 which may be considered as a stomach. Access to this is usually 

 provided by means of a mouth and a short O3sophagus, into 

 which the minute particles of alimentary matter are carried by 

 ciliary action. By the same agency they are conveyed to the 

 bottom of the cesophagns, where they are gradually collected 

 into a ball, and this when sufficiently large is allowed to pass 

 into the gelatinous fluid with which the stomachal cavity is filled. 

 Here the nutritive material is extracted from them whilst they 

 circulate in the cavity in the manner above described. 



1208. Putting aside the undetermined question of the in- 

 terior organisation of the digestive apparatus, we may pass to 

 the consideration of other phenomena presented by this remark- 

 able class. Food is usually conveyed to the mouth by the vibra- 



