OF INFUSORIA. 167 



various fruits, and upon many microscopic plants, I know that 

 where there are distinct currents running in tortuous channels 

 they constantly change their course, and by that evince their 

 freedom to move anywhere and at any time throughout one 

 common cavity ; whereas in the infusorian before us the line of 

 progress of the moving pellets, though a winding one, is fixed 

 within definite limits, and clearly under the control of some 

 guiding power. I have already pointed out the enormously 

 elongated throat of Epistylis, (fig. 95, g g- 1 ,) but I revert to it for 

 the sake of comparing it with the short one of Paramecium, and 

 to show by the extent of the former that it is not impossible 

 that its length in the latter may be carried equally as far, if not 

 farther, although in a less recognizable form. 



In this connection, I would like to say a few words in regard 

 to the celebrated theory of Ehrenberg, because I think that those 

 who have so positively denied the presence of the least trace of 

 the little saccular stomachs which that eminent observer has 

 asserted the Infusoria possess, are as far in the wrong as he, and 

 perhaps more so. I have copied one of the illustrations of Ehren- 

 berg, which he intended should exhibit the position of the stom- 

 achs, (fig. 98, 5, s 1 ,) and their relation to the 

 throat and mouth (m). He asserts that by feed- 

 ing the infusorians with indigo or carmine the 

 particles of colored matter may be seen to enter 

 the mouth, pass along the throat, and, entering 

 the cavity behind it, proceed to lodge themselves 

 in the little globular saccules or pouches, (s, s 1 ,) 

 which appear here to be attached to a central 

 sac or canal. Now it must be apparent to you that such a con- 

 figuration of the digestive system is altogether incompatible 

 with the mode of circulation of the food as I have described it 

 in Paramecium and Epistylis. Yet, under certain conditions, I 

 have seen what appeared to be the same as that which the 

 Berlin naturalist described ; but it seems to be explained by a 



Fig. 98. Chilodon cucullulus. Ehr. 200 diam. m, the mouth; s, s l , the 

 so-called stomachs ; cv, cv 1 , cv 2 , the three contractile vesicles. From Ehrenberg. 



