THE SLIPPBE AJSriMALCULB 15 



movements ? What causes their motions ? Do 

 they contract at the same time ? Expand ? 

 What becomes of their contents during con- 

 traction? How long is the time between two 

 consecutive contractions of the same vacuole ? 

 Is the time uniform? Compare the rate of 

 contraction or systole with that of expansion 

 or diastole. Are other parts of the body affect- 

 ed by the movements of these vacuoles ? The 

 motions of the contractile vacuoles are often 

 seen to advantage by allowing the water under 

 the cover-glass to evaporate, thus causing the 

 slow death of the animal. 

 5. Of the food -vacuoles. — What kind of motion is 

 it ? To what is it due ? Is it regular ? Do all 

 of the food - vacuoles move? Do all move in 

 the same direction? At the same rate? Are 

 they affected by the movements of the con- 

 tractile vacuoles ? Of what use is the motion ? 



h. NuVrition. 



1. Food and method of feeding. — Judging from the 

 contents of the body, what does the slipper 

 animal eat? By staining specimens with dilute 

 iodine, which colors starchy substances blue and 

 albuminous substances yellowish-brown, it will 

 be possible to determine the nature of some of 

 the ingested substances which cannot be recog- 

 nized by their shape. Watch the ingestion of 

 food-particles. How does it take place ? Is it 

 always through the mouth ? Is there any other 

 way for food to enter the body? Compare with 

 Amosha in this respect. How is the food swal- 

 lowed ? Study the formation of a food-vacuole. 



