LESSON XXXI 



RESPIRATION (Concluded) 

 ELIMINATION OF CARBON DIOXID AND CONSUMPTION OF OXYGEN 



1. The Elimination of Carbon Dioxid and Water. Exhale repeated^ 

 through a glass tube into a beaker filled with lime-water. Explain the 

 resultant turbidity. 



Procure a 4-ounce Woulffe bottle with three necks and the necessary 

 delivery tubes and stoppers; three 5-inch calcium chlorid tubes with 

 side tubes and perforated stoppers; a Geissler bulb with KOH and 

 CaCh tubes, two small flasks with stoppers, and two glass tubes; a 

 2-liter bottle in which the animal is placed ; and two 8-liter bottles. 



The tubes containing the calcium chlorid should be put in the dry- 

 ing oven at a temperature of 100 to 120 C. for several hours. They 

 are then cooled in a desiccator. Weigh two of them, marked e and /. 

 The Woulffe bottle and Geissler bulbs are filled with a 50 per cent, 

 solution of KOH. To the latter is attached the CaCl2 part and rubber 

 connecting tubes, which are then clamped. The whole is weighed. 

 The two flasks b and h are filled with a strong solution of Ba (OH) 2. 

 Weigh the bottle d into which the animal is to be placed later on. 

 Connect these parts and fill one of the siphon bottles (8 liters). Arrange 

 the other (k) at a distance of 1 m. below the filled one (i). 



Place a white rat into the 2-liter bottle and weigh. Connect this 

 bottle with the others. Start the siphon. Adjust the distance of the 

 siphon bottles so as to give a sufficient ventilation to the animal (indi- 

 cated by its rate of respiration). When the upper bottle has been 

 nearly emptied, clamp the tube connecting it with the adjoining flask 

 and quickly put the second (now filled) bottle in its place. Remove 

 the clamp, and again siphon. Continue this procedure for about one 

 hour. 



At the end of this period clamp the siphon tube, turn the stoppers 

 of the CaCh bottles, and disconnect the tubing. Weigh tubes d, e, 

 /, and g. Obviously, parts a, 6, and c remove the H 2 O and COz from the 

 air supplied to the animal, whereas parts e, /, and g collect the HsO and 

 CO2 given off by the animal in the course of this experiment. By weigh- 

 ing these parts before and after this test a means is provided for deter- 

 mining the amount of these excreta. 



Determine the loss in weight suffered by the animal during this test. 

 Ascertain how much H2O and CO2 left the animal during this period. 

 Do these amounts correspond to the loss in weight of the animal? 

 Explain. 



2. The Consumption of Oxygen. Fill the pressure tube B with a 

 solution of potassium pyrogallate, made by mixing 2 parts of a 25 per 



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