304 GEITERAL HISTOEY OF THE INFUSOEIA, 



to demonstrate the intestine connecting together the several gastric canities ; 

 and what is of more weight than the absence of direct evidence, are certain 

 facts subversive of the notion that any such tube exists, — ^dz. the irregularity' 

 in the course taken by the bolus of food when transmitted into the interior ; the 

 intermingling of the first- and last- swallowed morsels; the movements hither 

 and thither, and the actual rotation within the interior of the globules called 

 stomach-sacs ; the occasional coalescence of these sacs, and the not infrequent 

 occuiTence internally of frustules of Diatomece and joints of various micro- 

 scopic Algse of great relative length to the animalcule (XXYIII. 31) — some- 

 times, indeed, so long as to stretch the soft body itself (XXYIII. 1). On the 

 strength of these facts, coupled with the absence of demonstrative evidence 

 of its tiTith, the polygastric theory, and the system of classification founded 

 upon it, have together been all but universally rejected. 



Meyen was one of the fii'st seriously to examine the statements of Ehren- 

 berg : his conclusions were quoted at large in our last edition. He rejected 

 the polygastric hypothesis because he failed to discover the connecting intes- 

 tinal tube represented by Ehrenberg, and, on the other hand, detected the 

 rotation and coalescence of the assumed stomachs. His views of internal 

 organization closely tally with those now generally admitted. He recognized 

 the digestive tube, the formation of the globule of food at its apparently open 

 termination, and its onward coui\se into the interior of the animalcule, where 

 it constituted one of the supposed stomach-sacs. He seems, indeed, to have 

 imagined a sort of stomach-like dilatation at the end of the alimentaiy canal, 

 which served to hmit the dimensions of the food-globule there formed. The 

 circulation of the globules he attributed to the force of deglutition and to 

 the pressiu-e of others subsequently swallowed : the residue left after diges- 

 tion he described as escaping by an anus. 



An extract from Mr. Carter's valuable paper {A. N. H. 1856, xviii. p. 123) 

 may with propriety be introduced here. " I cannot," he says, " with some 

 others, think that there is any tatestinal canal in the abdominal cavitj^, be- 

 cause the digestive globules and other particles of food are constantly under- 

 going circulation roimd the wliole of its interior. In Vorticella, particles of 

 food may occasionally be seen to circulate throughout, and accumulate in 

 every comer of its interior, particularly those which do not happen to be en- 

 closed in globules. Moreover, the intimate resemblance which exists between 

 the alimentary organs of higher Infusoria (viz. Nassula, Otostoma, &c.) and 

 those of the binocular and so -called blind Plaiiarice — in the distance of the 

 mouth from the anterior extremity, the presence of a buccal apparatus, and a 

 simple sac -like stomach in the latter, lined with a layer of mucous substance 

 (sarcode ?), charged with the ^ spherical cells ' about to be described — is so 

 great, that, with such a simple gastric organ in an animal so closely allied to 

 these Infusoria as Planaria, I do not see what reason we have, in descending 

 the scale, to expect a more complicated digestive apparatus, but, on the con- 

 trary, one still more simple, in which there would be no stomach at all, — a 

 condition which appears to me to be common to all the Infusoria that have 

 come under my notice." 



The results of actual observation show that food is drawn into the mouth 

 by the action of its siuTOunding cilia, and is thence transmitted rapidly through 

 the pharynx and its continuation, the digestive tube, into the loose tissue of 

 the interior, assuming at first an elongated oval shape, but which soon changes 

 to globular in its passage. The food so introduced appears mostly like a 

 minute drop of water holding some solid particles in suspension, and presents 

 a clear areola around a darker centre. Its course in the interior seems to 

 depend on the varying force of projection exerted by the contractility of the 



