Mr Mej'en on the Digestive Organs of the Infusoria. 273 



which they present in the infusoria phmged in colourless li- 

 quids. In this case the balls are composed of a small num- 

 •ber of pai'ticles, and principally of a considerable mucous mass 

 which unites them. Sometimes two balls of this kind are so 

 l)ressed against each other by the contractions of the animal, 

 that they at last unite. 



If we wish to follow the formation of these balls, it is ne- 

 cessary to commence these observations at the moment when 

 the infusoria are plunged into the coloured liquid. The de- 

 glutition of the coloured particles takes place very quickly, 

 often in about half a minute, and the coloured balls issue, one 

 after another, from the stomach, and ai'e pushed downwards 

 along the internal wall of the cavity of the animal. In the 

 Paramascies, Keronies, and Vorticelles, the new ball pushes 

 the preceding before it along with the mucosities between 

 them, in such a manner that the first rises along the opposite 

 wall, returns to the other extremity of the cavity, and is 

 pushed downwards on the other side. The balls thus accu- 

 mulate in succession, till they are expelled, one after the other 

 by the anus. The number of these balls is often so consider- 

 able as to fill the whole cavity of the animal, and so close to- 

 gether, that they form a large mass, which turns slowly upon 

 itself, as among the Vorticelles. 



This rotation is the result of the force with which the newly 

 formed ball is pushed from the stomach into the cavity, and 

 moves along the under side of the preceding ball. In other 

 rases, Avhere there are not yet many balls, we lUiewise remark 

 the circular rotation alluded to, but I cannot in this instance 

 say what is the cause of it. 



Thus, in the true infusoria, the substances which they ab- 

 sorb are introduced into the abdominal cavity in the form of 

 balls, and from these the stomach extracts the nutritive sub- 

 stances. The residue remains in these same balls, the mucosi- 

 ties interposed are reabsorbed, and even in the interior of the 

 stomach the particles of the ball are disintegrated, although 

 this happens but seldom. 



What is the nature of those vesicular cavities, of such gi'eat 

 iuimV)ers, and so variable in si/.o, which appear in the interior 

 of the infusoria .'' They are not .stomachs ; they possess na- 



