Annml Report of the Royal Veterinwry College. 147 
In the preparation room morbid specimens are received, dissected, 
hardened, and sectioned, or otherwise prepared for examination in the 
microscope room ; and when suitable results have been obtained tliey are 
recorded for future use, if need be by means of photography, in the third or 
dark room. 
The atmosphere is full of bacteria or germs ; but fortunately the patho- 
genic organisms bear but a small proportion to those which seem to be harm- 
less in their nature. Nevertheless, the fact of myriads of such organisms 
being present in the air renders the investigation of bacterial diseases both 
tedious and difficult, on account of the liability to atmospheric contamination 
Fig. 1. — Steriliser ivith Reservoir. 
a, water in steam chamber ; h, supply tube ; c, lower chamber of reservoir ; d, communicating 
pipe ; e, reserroir ; /, air-tight cap with lever for filling reservoir ; g, air tube ; h, water gauge ; 
I, thermometer ; k, felt-covered lid. 
taking place during the necessafy manipulations. It has been found that 
bacteria are unable to survive the action of heat, and when this can be 
applied in a moist form a much lower temperature and a shorter time will 
be required to Mil them than if dry heat had been employed. "When by this 
means (or otherwise) freedom from these atmospheric interlopers has been 
secured, our instruments and apparatus may be considered in a fit state for 
further use — i.e., sterilised. Fig. 1 will give some idea of how this is carried 
out ; the vessel to the left is the well-known steriliser invented by Dr. Koch, 
and the suggestion that to Koch's steriliser should be added the reservoir 
■was first made by Dr. A. P. Aitken, of Edinburgh. 
L 2 
