520 



JOHN E. MUELIN" 



measured simultaneously by means of a gas meter driven by water power. 

 Samples taken by the aliquot method of Jaquet are analyzed for oxygen 

 and CO 2 by means of the Petterson analyser. 



The apparatus used by Krogh and Lindhard at Copenhagen is of the 

 Jaquet-Grafe type (Fig. 2). 



f. Apparatus of Haldane(a^). A convenient form of open circuit type 

 of apparatus devised for observations on small animals is that of Haldane 

 described in 1892. The respiration chamber (Figure 3) consists of a large 



Fig. 2. Diagram of the Jaquet-Grafe respiration apparatus used by Krogh and 

 Lindhard. The floor is made from a single sheet of galvanized iron with the edges 

 bent down into a U-shaped rectangular groove ( 1 ) which is filled with water. As 

 shown at (2) one end can be lifted to let in the subject and put in the apparatus; 

 (3) small tubes introducing wires, etc., for the working of the ergometer; (4 and 5) 

 ventilating tubes for use with a meter; (6) inlet for outside air; (7) side tubes 

 drawing air from points 50 cm. from the outlet; (9 and 10) fans for mixing the air; 

 (11) wet and dry bulb thermometers; (12) bottle of water keeping water level in 

 the meter; (13) hand sampling apparatus; (14) automatic sampling apparatus; (15) 

 tube leading from outlet to the automatic sampling apparatus; (16) thermometer in 

 the meter. 



bottle of 16 liters capacity. Air is aspirated through the bottle by means 

 of an ordinary laboratory water suction pump. The ingoing air is passed 

 over sulphuric acid in pumice stone and another bottle containing soda 

 lime. The outgoing air is likewise passed through three absorbers, the first 

 containing sulphuric acid, the second soda lime and the third sulphuric 

 acid. The gain in weight of the first gives the amount of water vapor 

 exhaled by the animal. The gain in weight of the second two gives the 

 amount of carbon dioxid exhaled. After passing the absorbers the air is 

 again saturated with moisture and measured by a gas meter. 



The apparatus is of such a size that the chamber with the contained 

 animal can be weighed. Loss in weight of the animal during an experi- 



