LABORATORY MANUAL OF PHYSIOLOGY. 



Under certain conditions, they assume a spherical form. Gen- 

 erally, however, they are seen undergoing constant changes of 

 form which, at times, may be very rapid. These changes consist in 

 the protrusion, from various parts of the outer portion or ectosarc 

 of the animal, of processes into which the more fluid interior por- 

 tion flows. Such processes are called pseudopodia. By the forma- 

 tion of pseudopodia, the animal is enabled to move about. This, 

 then, is a form of locomotion. 



The amoeba may contain one or more nuclei, usually only one. 

 In some part of the outer portion, a large, clear space in the proto- 

 plasm is seen, alternately, to grow larger and smaller. This is the 

 contractile vesicle or vacuole. 



Practicum. (a) Place a drop of amoebae-containing water, on a 

 slide. Cover with a supported cover slip. Examine with a low 

 power. Having found an amceba, examine it with the high power. 

 Make a drawing, indicating its main points of structure. Watch 

 an active specimen and make outline drawings from time to time 

 to show the change in form. Look for a specimen that is ingesting 

 food. What is the process ? 



(b) Observe the effect of heat upon the movements by using the 

 hot stage. 



(c) In the same way that you have studied the amceba, study 

 the white blood corpuscles of the frog and of man. To bring out 

 the nuclei, treat with dilute acetic acid. The slides for the study 

 of the living cells of man must be kept on a warm stage. 



(d) Into the dorsal lymph sac of a frog, inject an aqueous mixt- 

 ure of carmine or a fine suspension of lamp-black. After fifteen 

 minutes or a half hour, withdraw some lymph and examine for the 

 ingestion of foreign bodies by the white cells. 



2. Infusoria. These are protozoa having bodies of a constant 

 form and depending, for locomotion, upon flagella or cilia. The 

 flagella may be single or double and may be attached to one or 

 both poles of the organism. One of the most common found in 

 aquaria is Euglena viridis, having a long whip-like flagellum at one 

 end, by means of which it swims rapidly through the water. 



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