CYTOLOGY 



29 



FIG. 8 



paper and absorbent cotton; 50 per cent, alcohol; ether; saturated 

 salt solution; aqueous 10 per cent, solutions of iodine, of tannic 

 acid, of picric acid, and of nitrate of silver. 



2. Observations. Place a small drop of water containing euglense, 

 amcebse, paramcecia, vorticellse, or other protozoa on the center of 

 a perfectly clean cover-glass. If there are 

 anv drops of fibrous algae, as conferva or 

 spirogyra, the cover may be inverted upon 

 a clean slide and the animals studied. If, 

 however, there are no plants present, the 

 cover-glass may be supported upon a hair 

 laid across the slide, otherwise the cover will 

 settle down upon the animals and prevent 

 their free movements. 



After the cover is properly supported and 

 the organisms focused, make a careful study 

 of the forms present, describing their struc- 

 ture and such activities as are observed. 



To Determine the Influence of Carbon 



Dioxide upon the Activity of Animal 



Cells. 



1. Appliances. Microscope with high 

 power; ventilated, deep celled slide; ventila- 

 ting apparatus, consisting of reservoir, siphon, 

 and pressure bottle with connections as shown 

 in Fig. 11 (p. 34) ; aquarium stocked with pro- 

 tozoa; normal saline solution (NaCl 0.6 per 

 cent.); CO 2 gas generator. 



2. Exercises. (1) (a) Set up the ventila- 

 ting apparatus as shown in Fig. 11. The 

 slide should be clamped upon the stage of 

 the microscope with the help of the stage 

 clips. Disjoin the CO 2 flask at S and d; 

 fill and clamp the siphon; fill the flask with 

 CO 2 from the generator and replace it in 

 the apparatus; close both clamps. 



Mount a hanging drop of protozoa from the aquarium; focus 

 under high power. While watching the movements of the protozoa 

 loosen the siphon clamp; after the siphon starts, loosen the gas 

 clamp slightly to admit a little of the CO 2 . If after a half-minute 

 or more no appreciable change takes place in the rate of movement 

 of the cilia, repeat the dose of gas. What is the effect of CO 2 upon 

 the activity of protozoa? 



(b) After the effect of the gas has become apparent, clamp the 



Euglena viridis. A flagellate 

 infusorian. 



