6 Laboratory Guide in Zoology 



usually ahead? In case either of these is generally 

 in advance there is a differentiation into anterior and 

 posterior parts of the body. 



V. — As the Paramecium turns on its longer axis, notice 



whether the edges of the buccal-groove are covered 

 with cilia ; are these longer than those on the rest of 

 the body ? Are they constantly in motion ? Focus 

 carefully to see the gullet connecting the buccal-groove 

 with the interior of the body. Is this also lined with 

 cilia in motion .'' 



VI. — Run some powdered carmine under the cover glass : 

 when the particles have reached the Paramecium, 

 watch carefully to see some of them taken along the 

 buccal-groove through the gullet and into the body. 

 Notice that a little water goes in also, forming a 

 small, round food-ball that stops near the inner end 

 of the gullet, surrounded by the semi-liquid endosarc. 

 When another food-ball is taken in, the first one will 

 be forced along, keeping near the side of the body. 

 When a third mass is taken in, both the others will be 

 pushed along, and thus the process will continue, the 

 masses following a definite course around the outer 

 border of the endosarc. 



VII. — The course of the food-balls in the body may be 

 easily shown in this way : Place a lot of Paramecia 

 in a watch glass with a small quantity of water ; add 

 a little powdered carmine to the water; cover, and 

 examine fresh specimens at intervals of ten minutes 

 for an hour or more. You will be able to trace the 

 whole course of the food-balls by this method. 



VIII. — See the two round, nearly transparent contractile 

 vacuoles near the side of body, each about halfway 

 between the middle and the end. Watch them care- 



