iNFrSOniAT, ANIMALCTTT.tiS. S-T 



these stomach-cells, or eacs, has been filled with coloured food, and 

 its situation carefully noted, in a short time the coloiu-ed spot will 

 have changed its locality, and hence some naturalists will not admit 

 of sei^arate and distinct sacs or cavities, but maintain that the in- 

 terior of the creatiu-e is one large digestive cavity, and that the 

 globular mass of coloiu-ed particles has merely changed its position. 

 To this objection. Dr. E. remarks, that he has distinctly observed a 

 Bac to fill, and then the particles to pass singly into another, and so 

 on, until the nutritive portions having been imbibed by each cell in 

 succession, the refuse is expelled by the animalcule. That few 

 observers have noticed this process, is not remarkable, as it requires 

 stedfast and incessant observation of a particular animalcule for some 

 time, while a contraction of them, or a turning upon their axis, may 

 mislead, or even a slight pressui-e or other injury loosening these 

 cells, may occasion a volxintary change of place. Another objection 

 to their being sepai'ate sacs or cells for the purpose of digestion is, 

 that observers have not seen the canal or tube connecting them toge- 

 ther ; this Dr. E. admits is the case in many species, owing to its 

 extreme tenuity. Also, that from its peculiar office, namely, the 

 transmission of the food from one cell to another only, like the 

 oesophagus in large animals, the tube possesses a contractile action, 

 60 that the difficulty of detection is augmented. Dr. E. affirms he 

 has distinctly seen theii' canals while the food has been passing from 

 one stomach cell to another ; and in all his works, except Die 

 InfmionthiercJien, has presented us with drawings of them, and the 

 manner in which they connect all the cells together. Eor observa- 

 tions of this kind, it wiU be advisable to select a large specimen of 

 either of the following species: — Chilodon cucullus, Trachelius Ovum, 

 Vorticella chlorostigma, or V. convallaria, Opercularia articulata, or 

 Stylonyckia Mytilus. 



Again, the position of the discharging orifice has favoui'ed the 

 erroneous supposition of the excluded substance being ova, for this 

 orifice is not situated in any certain relation to the mouth ; for 

 sometimes one orifice is common to both purposes, as in the fresh 

 water Polj-pe, and some other large creatures. In other Polygastricaf 

 it is either situated anteriorly, posteriorly, or laterally, and this again 

 may be either on the superior or inferior side. On this charactet^ 



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