OF THE PROTOZOA. CILIATA. 309 



ence for a certain space, so that, if it differs in its colour or turbidity from the 

 water of the sea or pool, we may distinguish it from the latter (with which 

 it does not mix for a long time) in the form of a streak, w^hich is often of 

 great length. 



*' ^\Tien the nutritive particles in the body of the Vorticellce have attained 

 the end of the clear streak under a constant diminution of theii' rapidity — and 

 in the other case, when the morsel has lost its spindle-shape and become glo- 

 bular — they have no longer any separate movement, but now only take part 

 in a circulatory motion, in which all the parts in the interior of the body, 

 with the exception of the nucleus and contractile vesicle, are engaged." 



This account applies in general to the alimentary mechanism of all other 

 Ciliata besides the VorticelUna, except so far as concerns the dilated lower 

 half of the oesophagus (/. e. pharynx of Lachmann), which is never seen. 

 The cihated oesophagus ends by an obliquely truncate extremity, through 

 which the di^ap of water introduced by the mouth enters the tenacious fluid 

 mass of the interior, where it expands into a rounded vacuole or stomach-sac, 

 which continues its onward ciu-vilinear course until, by absorption or by ex- 

 pulsion thi'ough the anal outlet, it disappears. Yet it may happen, just as in 

 the VorticeWma, that the water and food, instead of, as usual, being united 

 into di'ops and morsels, may be mixed at once with the contents of the abdo- 

 men, and no semblance of a fuU vacuole be produced. 



A remarkable fact is recorded by Lachmann, of the digestive organization 

 of Trachelius Ovuin, in which, by the way, Ehrenberg declared the alimentary 

 canal was more easily seen than in any other animalcule. " In Trachelius 

 Ovum/' writes the author we quote (p. 127), " alone we see a proper stomach- 

 wall separated from the rest of the parenchyma by spaces filled ^\dth fluid, 

 and thus form an arborescent ramified canal, which, however, must not be 

 confounded with the nucleus." To this statement he adds, in a foot-note, 

 — " The animalcules devoured (Trachelius Ovum is one of the most voracious 

 robbere) are always seen lying in the ramifications of the stomach, in the clear 

 spaces between them, except in crushed animals. The clear round spaces in 

 the parenchyma (cortical lamina) of the body, are certainly no stomachs, but 

 contractile spaces." This structure was affirmed to the wi'iter by Lieberkiihn, 

 and was, no doubt, seen by Ehrenberg, but misunderstood by him in most 

 points. Its gastric character, however, has not past unchallenged, for both 

 Cohn and Leuckhart (AYiegmann's Archiv, Bericht, 1855) assert that it is no- 

 thing more than a fibrous band extending inwards from the integument in 

 difl'erent directions through the soft contents of the interior. In this expla- 

 nation Gegenbauer seems to agree — the granular bands described by this 

 observer under the name of '' trabecuUe " appearing identical with the fibres 

 of the two last-named writers. These trabeculce are stated to be contractile 

 and to have a definite arrangement, the principal one extending backwards 

 from the long, ciliated, oral fissure along the same side of the body, and ha^dng 

 secondary trabeculae branching from it and proceeding to the cortical lamina, 

 where they are lost. And although Gegenbauer speaks of an intestine-like 

 structure prolonged backwards from the mouth, in which numerous food- 

 globules could be seen, yet he says that there was no perceptible difference 

 in structure to distinguish this so-caUed intestine from the rest of the body. 

 Moreover he notes that the nutritive globules may be often seen passing 

 through the smaller trabeculae. Besides the oral fissiu'e, he remarked another 

 opening situated further forward than it, beneath the motile proboscis, Avhere 

 the tegumentary wall is thick, and connected with a trabecula extending 

 inwards to unite with others. This opening he found to be constant in size 

 and position, to be prolonged inwards to the chief trabecula as a wide 



