INFUcORIA AND RHIZOPODA. $$ 18, 14. 
28 
§ 13. 
If the vesicular cavities containing the liquid and colorless food of the 
Stomatoda be examined under the microscope by a horizontal central inci- 
sion, their contents appear colorless; but by changing the focus, viewing 
alternately the convex and concave surfaces of the vesicle, the points of 
junction between the colorless globules and the parenchyma appear colored 
pale-red. This appearance, due to an optical illusion, might easily deceive 
one into the opinion that the vesicles which are really colorless are colored. 
From this it is probable that Ehrenberg has described Bursaria vernalis 
and Trachelius meleagris as having a red gastric juice.” 
The violet points which are found upon the back and neck of Nassula 
elegans and Chilodon ornatus are only collections of pigment granules, 
which, in the first case, are often absent, and in the second are often par- 
tially dissolved. 
This last violet liquid has been regarded by Ehrenberg® as a gastric 
juice resembling bile 
§ 14. 
The solid particles of food, whether surrounded by the parenchyma or 
enclosed ina liquid vesicle, are moved hither and thither in the gelatinous 
tissue of the body, during the contracting and expanding movements of the 
animal. In some, the parenchyma with its contained food moves in a reg- 
ularly circular manner, like the liquid contained in the articulated tubes of 
Chara. In Lozodes bursaria this circulation is remarkable, and of much 
physiological interest. ts cause is yet quite unknown, for in no case is it 
due to cilia, and it may be observed in individuals entirely at rest. Ehren- 
derg,® therefore, is incorrect in regarding it as due solely to a contratile 
power of the parenchyma, displacing the molecules. Much less is his ex- 
planation satisfactory, since the digestive tube of an infusorium can be 
extended at the expense of its stomachal pouches, so as to fill the whole 
body, giving it the appearance of having a circulation of molecules through- 
out its entire extent, 
1“Die Infusionsthierchen,” pp. 321, 326, 329. 
Ehrenberg has, rooreover, in T'rachelius melea-  p. 75. 
gris, confounded the contractile cavities with those 2 Focke loc. cit.; also Erdl, Miller’s Arch. 1841 
non-contructile, and which receive the food. p. 278. 
me p. 786; also Meyen, Muiller’s Arch. 1839, 
2 Abhandl. d. Berliner Akad. 1833, p. 179 5 also 
“ Die Infusionsthierchen,” pp. 319, 338, 339.* 
1 Vaginicola and Vorticella. See Focke, Isis, 
Diatomacez, portions of Algae or Desmidieae, and 
with fragments of variously colored cotton, woolen, 
and linen fibres, will give a picture of the animal ; 
to complete which, it is only necessary to add a 
few loose strings to the bag to represent the varia- 
ble radiant processes which it possesses around the 
mouth.” This animal, which is often found with 
bits of cotton protruding from its mouth, assumes 
the most bizarre shapes. They appear to multi- 
ply by fissuration and gemmation even when filled 
with tnese heterogeneous particles, and, on the 
whole, present characteristics as remarkable az 
8 Loe. cit. p. 262. 
4 Muiler’s Archiv. 1839, p. 81. 
those of any animaleule with which we are ac 
quainted. — Ep. 
*[§ 13, note 2.) In this connection should be 
noticed the experiments of Will (Miiller’s Arch. 
1848, p. 509). He found evidences of a biliary ap- 
paratus, with Vorticella, Epistylis, and Bursaria. 
These evidences are based on chemical re&ction, 
and he describes no anatomical apparatus. I men- 
tion this fact here, although Vorticella belongs 
truly to the Bryozoa, and Bursaria to the Plana- 
ria. — Ep. 
