NUTRITION LABORATORY. 277 



features should be added. The amount of research thus far carried out 

 on the relationship between direct and indirect calorhnetry has shown 

 conclusively that an extensive series of observations can advantage- 

 ously be made with such a respiration chamber without compUcating 

 the apparatus by delicate calorimetric features. A large respiration 

 chamber has therefore been built by the Laboratory mechanicians in 

 the respiration calorimeter laboratory. This chamber is 5.2 meters 

 long, 3.8 meters wide, and 2.3 meters high, with a water-sealed opening 

 at the top and large plate-glass windows at one end, permitting day- 

 light illumination. In studies carried out with this apparatus, empha- 

 sis will be laid upon the determination of carbon dioxide developed 

 under various conditions. 



APPARATUS FOR THE MEASUREMENT OF LARGE AMOUNTS OF CARBON DIOXIDE. 



The universal respiration apparatus is so adaptable that it has 

 already been employed for researches varying as widely as the measure- 

 ment of the gaseous metabolism of a single guinea-pig and of the 

 carbon-dioxide production of a man working to the limit of human 

 endurance. In this latter study the apparatus effectively absorbed 

 from the ventilating air-current as much as 3 liters of carbon dioxide per 

 minute. The quantity of chemical reagents required under such 

 conditions to remove the carbon dioxide completely prohibits the use 

 of this apparatus for experiments over long periods of time. Accord- 

 ingly, in researches in which large amounts of carbon dioxide are to be 

 absorbed, such as studies of the metabohsm of large animals (par- 

 ticularly domestic animals) , of a group of men, women, or children, or 

 of one or two men working continuously at severe muscular labor, a 

 very different type of respiration apparatus is required. Using as a 

 basis a novel method for samphng a large air-current, we have devised 

 an apparatus which gives excellent results in the measurement of con- 

 siderable amounts of carbon dioxide. When the apparatus is attached 

 to the large respiration chamber previously mentioned, it makes possi- 

 ble all types of experimentation with a number of individuals or under 

 conditions of severe muscular work. 



MINOR APPARATUS. 



For the permanent retention of many of the unique processes devel- 

 oped in experimentation on man, it has been found advisable to take 

 cinematograph records of the various techniques. Consequently, 

 the Laboratory has been equipped with a suitable cinematograph 

 camera and projection apparatus for this purpose. The films are of 

 marked advantage in showing technique when, for one reason or another, 

 apparatus has been dismantled. 



An electrically-driven kymograph constructed by Schloer, of Bowie, 

 Maryland, has also been added to the equipment of the Laboratory. 



