NUTRITION LABORATORY. l8l 



completed late in the spring and has been in almost constant use since that 

 time. It has been very satisfactory, and is much more easily manipulated 

 than the first apparatus. A third apparatus is now in process of con- 

 struction. 



RESPIRATION APPARATUS FOR DOGS. 



For use in an investigation in which dogs were employed for subjects, a 

 respiration apparatus was constructed of galvanized sheet-iron with a capac- 

 ity of about i cubic meter. The apparatus was constructed on the closed- 

 chamber principle, and in use the animal was placed inside the chamber and 

 analyses of the air made periodically, the rise in carbon dioxide being noted. 

 This apparatus proved very serviceable. After the routine and method of 

 procedure had been thoroughly established, however, it was found that the 

 apparatus was somewhat too large for securing the most accurate results 

 with the small dogs required for the particular research in progress. A sec- 

 ond respiration apparatus was therefore constructed upon the same principle 

 with a cubic content of only about one-third of a cubic meter. This ap- 

 paratus has been used almost exclusively since its construction and gives 

 perfectly satisfactory results. The chamber is in the shape of a cube, with 

 a cover placed upon the top closed with a water-seal; on one side of the 

 chamber is constructed a supplementary apparatus to determine the activity 

 of the subject. The movements of the animal confined in the small cage 

 which is fastened inside of the apparatus result in a vertical displacement of 

 a pointer which records the variations upon smoked paper. Samples of air 

 are periodically withdrawn and the carbon dioxide determined. Only the 

 variations in the carbon-dioxide content have thus far been studied. 



ADIABATIC CALORIMETER. 



The new adiabatic calorimeter mentioned in the last report has been im- 

 proved and completed, and it is now in permanent useful condition and has 

 been in constant use during the past year. The results have been extremely 

 satisfactory, less time being required for the determinations and its manipu- 

 lation being much easier. 



CHANGES IN THE CALORIMETER LABORATORY. 



Much of the construction in half of the respiration calorimeter laboratory 

 is practically completed, and instead of relaying the floor, as was originally 

 planned, it was decided to cover the floor with linoleum. The heaviest grade 

 of linoleum was used and cut and laid so that it would be possible, for repair 

 work, etc., to easily uncover the troughs through which the piping runs. 

 This floor covering has been very satisfactory. 



As originally constructed, the respiration calorimeter laboratory had a 

 head-room of about 15 feet and in some parts of the room this is not utilized. 

 Since so large a portion of the floor space was being used for the respiration 



