ELEMENTARY VITAL PHENOMENA 



153 



remain for a long time in the concavity which the sausage-shaped 

 nucleus turns toward the interior of the cell, there chiefly to 



FIG. 51. An elongated pseudopodium of Lieberkuhnia in which an ini usorian (Colpidium colpoda) 

 has become caught ; o, b, c, d, e, /, various stages of digestion of the inf usorian. 



undergo destruction. This indicates that very probably the nucleus 

 takes an important share in the digestion of the food-masses. 

 Just as proteids are transformed by pepsin in an acid and by 



