58 GENERAL &IOLOGY 



way to observe this groove, the buccal groove, is to watch 

 the animal as it rotates on the long axis (use the low power). 

 In the clay model already constructed indicate the position 

 and shape of this groove. 



Examine with the high power. If the movements are 

 not sufficiently restricted to allow the examination of speci- 

 mens with the high power, place them in a rather thick 

 gelatin solution, which will retard their movements. Or one 

 may try the following scheme: on a slide without cotton place 

 a drop of the water containing the animals and cover with 

 the cover glass. With a piece of filter paper applied to the 

 edge of the cover glass slowly draw some of the water from 

 under the cover. Continue until the cover begins to touch 

 the animals and to flatten them slightly. At this point it 

 will be found that the paramecia do not have room to move 

 about and, being flattened somewhat, the internal structure 

 is more evident. The success depends upon the remova 

 of just the right amount of water. Remember the shape 

 of the animals under these conditions is considerably dis- 

 torted, and some of the structures are not normal. 



Can you distinguish an ectoplasm and an entoplasm? In 

 what ways are these like, or unlike, the same parts of amoeba? 

 In a quiet specimen observe the ectoplasm carefully and 

 look for a delicate outer layer, the cuticle, which serves as 

 a cell wall. Fine, hair-like, protoplasmic processes, the 

 cilia, project from the surface of the body. Are these cilia 

 present on all parts of the body? Are they of uniform 

 length? In the deeper part of the ectoplasm are minute 

 oval sacs called trichocysts, arranged perpendicular to the 

 surface. Very often they look like short stiff rods rather than 

 sacs. The contents of these sacs may be forced out beyond 

 the cilia, or even entirely out of the body, and appear as 

 rather thick threads in the water. The tangle of threads 



