INFUSORIA. 93 
alimentary system attributed to these creatures by the German 
physiologist. He laboured to establish the fact that the coloured 
globules which appeared in the bodies of the Infusoria, while sub- 
jected to a regimen of carmine and indigo, are not confined by a 
membrane ; that is to say, they are not contained in special alimen- 
tary sacs, and that these so-called stomachs are, as stated by Milne- 
Edwards, “nothing but a species of reservoirs, constituted,” as he 
says, “by the alimentary matter with which each is gorged, united 
into a rounded pasty mass, so that it could no longer be dispersed, 
but would continue to advance, still preserving its form. We have, 
in short, seen these spherules changing their places, and passing one 
another in their progress from the mouth through the intestinal canal. 
That they could not do this is evident, if many stomachs were 
attached to the intestinal canal !” 
This opinion, due to the patient and precise studies of Dujardin, 
has been adopted by most naturalists of eminence. Besides, this 
learned microscopist does not admit that there was in the sarcodic 
mass of Infusoria any pre-existent special alimentary cavity destined 
to receive the food. In a word, he does not recognise in them any 
true stomach whatever. This view of the extreme simplicity of 
structure in the Infusoria has, however, met with opposition even by 
some recent writers. To accord them neither four nor two stomachs, 
it is not necessary to deprive them of the organ altogether. Meyen 
represents them as having one great hollow stomach occupied by a 
pulpy matter, into which the alimentary masses are successively 
absorbed. ‘All recent observations,” says Milne-Edwards, “tend to 
establish the fact that the digestive apparatus of the ciliate Infusoria 
consists of—first, a mouth ; second, of a pharyngeal canal, in which 
the food often assumes the form of a do/us, third, of one great 
stomach with distinct walls, and more or less distant from the com- 
mon tegumentary membrane ; fourth, of an excretory orifice.” 
This mouth presents sensible differences, both as to its position 
and conformation, often occupying the bottom of a hollow, the edges 
of which are furnished with well-developed ci/ia, the action of which 
attracts the aliment ; in short, the mouth is a sort of decoy at the 
bottom of a simple pit, being at once contractile and prehensile, the 
interior part being sometimes capable, according to Milne-Edwards, 
of being turned inside out in the form of a trumpet, while in a great 
many species it is provided with a peculiar armature, consisting of a 
band of rigid bristles disposed in the form of a bow-net, and suscep- 
tible of dilatation and contraction, according to the wants of the 
animal. The cesophagus, which is connected with the mouth, has 
