﻿INSTITUTE OF PHYSIOLOGY
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mice, and rats; (6) a middle calorimeter for dogs, cats, and rabbits; (c) a calorimeter for man and large animals. The principle of these three types is that we calculate the heat given off by the living being by determining how many calories must be developed by a heated wire in another room in order to have an equivalent caloric output between both the sources of heat. The latent heat required by the living being for the transformation of water into water vapor is counterbalanced by producing an equal quantity of latent heat in the other room.
This double differential principle is realized for man in the following manner by constructing two adiabatic thermostats. Two small rooms, 1.70 by 2.40 by 2.20 meters separated by a central corridor are surrounded by different insulating materials, air, wood, paper, cork, and masonry. One of the rooms is designed for receiving a living being; the other contains an electric resistance which can be heated by a variable electric current from the outside. The amount of the compensation heating current is read on an ampero-meter. To take away the developed calories, both rooms are cooled by water currents circulating in serpentine, which cover the walls and the ceilings. This water is measured upon its absolute temperature by thermometers sensitive to one one-thousandth of a degree, Celsius. The equivalent of temperature in the rooms can be determined by comparing the temperature of the water currents or better by bolo-metric wire systems, spread out in the interior of the calorimetric rooms and forming two arms of a Wheatstone bridge with a sensitive galvanometer as an indicator. Screens of fine copper gauze contribute for equal repartition of heat, and large fans of a special pattern are distributing and mixing the air to secure the same degree of temperature and humidity everywhere.
We determine the total caloric output by calculating the equivalent of heat given off by the electrical resistance. The equivalent of latent heat is determined by the equivalent of humidity measured in the two rooms by means of dry and wet thermopiles placed in air currents withdrawn from the two rooms. The amount of humidity needed is obtained by evaporating water of a spray which is regulable from the outside.
The calorimeter is employed with very good results for all metabolic research, but especially for the basal metabolism of man, where we can follow the caloric output from the moment of entrance until the moment of minimal deperdition.
DEPARTMENT OF SPECIAL SENSES
The western part of the first floor of the main wing is occupied by rooms which form the Department of the Physiology for the special senses. This department comprises two pairs of rooms separated by a
large dark room, No. 49. There are openings in the wall between the dark room and the adjacent room to make it possible to register photographically experiments that are running in the adjacent rooms. The two southern rooms, No. 50 and 51, are arranged for different optical work; there is accommodation to employ direct sunlight for different purposes. The northern pair of rooms, No. 47 and 48, constitute the laboratory for acoustics, containing a special laboratory for phonetics.
The laboratory of phonetics (Fig. 12) is directed by a
Fig. 12.—Department of Phonetics
philologer who can appeal to experimental physiology for his experimental work. The director with his students is occupied with researches concerning the repartition of dialects spoken in Belgium. This study is particularly interesting because Belgium represents a meeting place of the Germanic and Latin languages.
ASEPTIC DEPARTMENT
The Aseptic Department, suggested by the ideas and the experience of the Russian physiologist Pavlov, comprises :
(a)	A sterilization and preparation room (No. 74) provided with a steam sterilizer and the necessary arrangements for the sterilization of instruments by boiling. There are additional wash basins with hot and cold water supply and a cupboard with instruments.
(b)	An operating room (No. 75) having daylight from three sides and a strong electric lamp of 400 candle power, fixed on the ceiling. This room separated from the rest of the department has a large interior heating surface secured by means of radiators, and ventilating openings near the ceiling. The operating table which is heated by electric lamps closed up in a