332 BACTERIA. 



tables may be kept clean. Two tables placed parallel to one 

 another in the centre of the room are used for chemical 

 operations which cannot be carried on at the smaller special 

 tables. Then there are large evaporating chambers, in which 

 are placed the sterilizing and incubating apparatus. In 

 addition to the incubating apparatus used in the common 

 laboratory, there is a large common room, which is really 

 made up of three rooms : An entrance chamber, in which 

 the temperature varies somewhat from time to time ; it con- 

 tains the heating apparatus, and is specially designed as an. -air 

 cushion insulator. The second chamber nine feet ten inches 

 long, eight feet broad, and six feet high is heated by means 

 of hot water, by which it is kept at a constant temperature. 

 Above this, and heated in connection with it, is a third 

 chamber, in which the temperature is intermediate between 

 those of the two preceding ones. This group of incubating 

 chambers has very little cooling surface, and is separated 

 from the outer wall by a room in which is collected and 

 washed all the dirty glass used in the laboratory. In these 

 constant-temperature chambers are shelves and tables, on 

 which may be seen all kinds of flasks, test tubes, and sterilized 

 moist chambers, in which, growing on various media, and 

 under different conditions, are all kinds of micro-organisms 

 that are being experimented with in the various departments 

 of the Institute. The laboratory " preparateur " has a room 

 next to the laboratory, with which it communicates directly, 

 so allowing ready access thereto and constant superinten- 

 dence. From this small laboratory is the only entrance to 

 the museum, for the care of which the preparateur is directly 

 responsible. A special laboratory for the performance of 

 experiments in chemical biology, and a lavatory, are also 

 added to the suite on this floor. The laboratory and the 

 room of the director of the department are placed in each 

 wing. These are entered from the passage which leads to 

 the common laboratory. In the storey above this there are 

 no teaching laboratories ; we have simply two series of 

 rooms, divided by a passage, each room designed to become 

 a research laboratory, and fitted up to meet the require- 

 ments of the savant who occupies it. Investigators have 

 every facility for carrying on their work, and may, if 

 they desire it, have the advice and guidance of any of the 

 directors of departments, each of whom is responsible for the 



