Dr. Griffith on the Sacculi of the Polygastrica. 445 



to us by their contents, and in many cases there are no stomachs 

 visible when they are empty, and it is their contents which we see 

 circulating or moving in their proper canal or alimentary tube, 

 and not the sacculi themselves. The motions of these masses 

 may not inaptly be compared, but merely for the sake of illus- 

 tration, to those of the alimentary masses in our own intestines ; 

 the revolution of these (if viewed under similar circumstances) 

 would produce the appearance of circulation ; when the masses 

 have arrived at the termination of the canal they are ejected, but 

 here the portion of tube or stomach is not ejected. This compa- 

 rison exemplifies to my mind the true nature of the sacs in the 

 Infusorial Polygastrica. 



"We certainly cannot admit, as in the explanation of Prof. 

 Ehrenberg, that the rotation of the globules or balls of aliment- 

 ary matter takes place in a cavity formed from a distended por- 

 tion of the alimentary tube. We see this rotation when the 

 intestinal tube is very slightly distended and when the balls of 

 food are very small; but I believe it to be capable of expla- 

 nation in the manner I have stated ; the appearance of one of 

 the sacculi when really distended is so readily recognised that it 

 could hardly be mistaken ; but the stomachs (i. e. their contents) 

 have been seen to rotate, by observers, when neither the animal- 

 cule nor its stomachs are at all distended ; and undoubtedly this 

 is a real rotation, not an optical illusion from any peristaltic 

 action. Moreover the rotation of these bodies is so constant as 

 to be considered as their ordinary state; whereas, did it arise only 

 in distended states of a stomach or the alimentary tube, it would 

 be rare, or at least only to be seen when the animalcule takes in 

 a large portion of aliment ; and I think that any one who has 

 distinctly seen (as I often have) various floating alimentary 

 particles taken in at the oral orifice separately, then accumu- 

 lating into a small ball, and this ball descending in the body of 

 the animalcule, and ' c circulating " as I have described, will be 

 convinced that this explanation is correct. 



I cannot believe they are recesses from a common tube ; I have 

 never been able to detect a horizontal or retrograde course 

 which would be pursued by the boluses, were such the case. 

 The alimentary canal is most commonly in a convoluted form, or 

 coiled; and there is doubtless a difference in the extent and 

 arrangement of the tube in those which feed upon other animal- 

 cules and those on vegetable matter. The fact of the portions 

 of food contained in their sacculi being gradually approximated 

 to the surface of the depression, and there being separately 

 emptied, is, I think, a clear conviction that there can be no single 

 stomachal cavity, and also, that the rotation of particles does not 

 take place in a single dilated tube. Moreover it must be recol- 



