THE SIMPLER ORGANISMS 73 



tory apparatus and reagents, a little dry carmine, and a 

 2% solution of gelatine, or its equivalent. 



The student should perform the work of the following 

 outline : 



1 . Obtain a drop of water containing paramoecia upon a 

 slide. Examine it uncovered with a simple lens to make 

 sure that the animals desired are present. A little trash 

 from the jar included in the drop will be of assistance in pre- 

 venting the cover glass from coming down too close and crush- 

 ing the animals. Numerous smaller, but similar infusorians 

 are likely to be associated with Paramoecium, and often the 

 phenomena of division are more commonly found among 

 these. 



2. Before applying the cover glass, survey the contents 

 of the drop with low power of the compound microscope, 

 and, by moving the slide, follow some of the paramoecia as 

 they go swimming about. Observe the spiral course of the 

 swimming,. and the resultant rapid motion directly forward. 

 Observe also the habit of the animal when it meets an ob- 

 struction: note the slight backward motion before the turn- 

 ing aside. 



3. Apply the coverglass, with plenty of water under it, 

 so that there will still be room for swimming. Find a place 

 where a paramoecium is repeatedly meeting with obstruc- 

 tion to his swimming, and observe what relation the direc- 

 tion of his turning aside bears to the position of the oblique 

 groove (oral groove} down one side of the anterior end of the 

 body. Observe also, the rolling motion of the body in 

 swimming, and determine what relation the position of the 

 mouth bears to the axis of the spiral course in which the 

 animal swims. 



4. Withdraw some of the water from under the cover- 

 glass with a blotting paper strip held at the edge, so as to 

 confine some of the animals in close quarters. Find a place 



