Note on one side, beginning at the anterior end, the _buccal groove_ leading into the interior through the _gullet_. Observe also that by the action of the cilia in the buccal groove food-particles are swept into the gullet. Rejected or waste particles are ejected from the body occasionally. Where? Note about midway of the _Paramœcium_ an ovoid body with a smaller oval one attached to its side, the former being the _macronucleus_, the latter the _micronucleus_. Note that there are two contractile vacuoles in the _Paramœcium;_ also that the food-vacuoles have a definite course in their movement inside the endosarc. Make a drawing of a _Paramœcium_. In comparing _Paramœcium_ with _Amœba_ it is apparent that the body of the first is less simple than that of the second. The definite opening for the ingress of food, the two nuclei, the fixed cilia, and the definite cell-wall giving a fixed shape to the body, are all specializations which make _Paramœcium_ more complex than _Amœba_. But the whole body is still composed of a single cell, and there is, as in _Amœba_, no differentiation of the body-substance into different tissues, and no arrangement of body-parts as systems of organs. _Paramœcium_ may occasionally be found reproducing. This process takes place very much as in _Amœba_. The animal remains dormant for a while, the micronucleus then divides, the macronucleus elongates and finally divides in two, the protoplasm of the body becomes constricted into two parts, each part massing itself about the withdrawn halves of the macro- and micro-nuclei, and lastly the whole breaks into two smaller organisms which grow to be like the original. After multiplication or reproduction has gone on in this way for numerous generations (about one hundred), a fusion of two _Paramœcia_ seems necessary before further divisions take place. This process of fusion, called _conjugation_, may be noted at some seasons. Two _Paramœcia_ unite with their buccal grooves together, part of the macronucleus and micronucleus of each passes over to the other, and the mixed elements fuse together to form a new macro- and micronucleus in each half. The conjugating _Paramœcia_ now separate, and each divides to form two new individuals. [Illustration: FIG. 6.--_Paramœcium_ sp.; buccal groove at right. (From life.)] CHAPTER VII THE SINGLE-CELLED ANIMAL BODY.--PROTOPLASM AND THE CELL