LABORATORY MANUAL OF PHYSIOLOGY. 



form a complete circle, but rather a spiral, which passes down the 

 tube leading from the mouth and known as the esophagus. There 

 is a sausage-shaped or spiral nucleus and a contracting vacuole. 

 The stalk may be seen under the high power to contain a core of 

 contractile protoplasm. 



Practicum. (a) Place a little powdered carmine in the water 

 containing vorticellae. Examine under the microscope. What be- 



FlG. 3. Paramecium. i 

 and 2, Contracting vacu- 

 oles ; 3, nucleus ; 4, mouth ; 

 5, stomach ; 6, food parti- 

 cles. 



A. 



FIG. 4 Vorticella. A, Open, stalk extended 

 B, closed, stalk coiled, n, Nucleus ; v, vacuole 

 f, food particles. 



comes of the carmine ? Note the motion of the cilia. Follow the 

 movement of the food vacuoles. Note the movements of the ani- 

 mal as a whole. What is the function of the stalk ? If opportunity 

 offers, observe the process of multiplication. 



(b) Effect of various gases upon the activity of protozoa. Car- 

 bon dioxide. Arrange a deep-celled slide in such a way that a 



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