312 GENERAL HISTOEY OF THE INFUSORIA. 



same process ; so is also the special production of cuticular matter in the con- 

 struction of the dense resisting shields and urceoL* of loricated species, e. g. 

 Coleps, or that of the substance used in the formation of stems and of 

 external sheaths. Another instance of a secretion maybe seen in the solvent 

 fluid poured out for the solution of solid particles of food in the interior, — a 

 fluid certainly not demonstrable apart, but presumable from the phenomena 

 of digestion. 



Having observed the particles of food in the abdominal cavity to be fre- 

 quently surrounded by a clear space filled mostly with colourless, but some- 

 times ^vith a coloured liquid, Ehrenberg at once attributed to it a digestive 

 faculty, and termed it the bile. He speaks of this in the history of the genus 

 Bursaria, where it is stated to be either coloiuiess or reddish. In Nassula, 

 again, lie figures biliaiy glands in the shape of vesicles forming a mde circlet 

 around the mouth, filled with a violet- coloured juice, which is discharged 

 with the excrementitious particles, and which at first appears like di'ops of 

 oil, but soon mixes with and becomes diffused through the water. The 

 following species are enumerated as possessing one such vesicular gland : viz. 

 Chilodon ornatus, Bursaria vernalis, Traclielius Meleagris, AmpliUeptus 7iuir- 

 garitifer, A. Meleagris, and A. hngicollis. 



The bodies thus represented by Ehrenberg as vesicular glands have not 

 escaped the notice of Stein, who pronoimces distinctly against their glandular 

 natui'e, and insists upon theii' being nothing but sections or joints of the fibres 

 of the Oscillatorice and other plants that the animalcules feed upon, and which, 

 in the course of their digestion, change from green to a dusky blue, afterwards 

 to a reddish-brown colour, and at length, when broken up, become difiiised 

 throughout the interior, and impart to the entii^e animalcule a reddish- 

 yellow hue. 



Cohn {Zeitschr. 1857, p. 143) has remarked in Nassula elegans numerous 

 granules of a yellowish -brown and violet colour, either collected into heaps 

 or scattered through the interior. On the under smface, near the anus, is 

 usually a large violet mass, and at the opposite extremity a similar smaller 

 one, which have been described by Ehi^enberg as biliary glands (XXYIII. 11, 

 12). If they are not particles of vegetable -coloured food altered in hue by 

 the process of digestion or solution, they may, says Cohn, be considered 

 analogous to the chlorophyll-corpuscles of Paramecium (Loxodes) Bursaria, 

 of Sjpirostomum, or of Vorticella viridis, and a special form of colouring 

 matter. The collection of the coloured mass about the anus, and its dis- 

 charge in the shape of bluish particles — facts noticed by Ehrenberg — indicate 

 its nature to be effete and excrementitious. Yet it is not the mere crude 

 joints of OsciUatoria, as Stein supposed, but matter which has been digested. 

 The heap about the neck is by no means constant. 



Contractile Yesicle. — Passing now to the other contents of the Ciliata, 

 the contractile vesicle or space first arrests our attention. Mr. Carter would 

 call it simply the ' vesicula ; ' but this word, without the adjunct " contractile " 

 to particularize it, seems insufficient, especially when the Latin language is 

 used in description. 



This organ is of universal occurrence among the Ciliata ; it is mostly single ; 

 but in a few instances two and even three such, mostly of unequal magnitude, 

 occur. It did not escape the notice of Ehrenberg, who has figured it in all 

 his plates of these beings. It occurs as a clear, hoUow, mostly roimded space 

 in the interior, its precise position differing in different species. It is always 

 placed in, or closely connected with, the cortical or contractile lamina, and is 

 not affected by the circulatory current. In the great majority of species it 

 is situated nearer the anterior extremitv, and in verv close relation with the 



