THE BACTERIOLOGICAL MICROSCOPE 5 



decidedly less. The cost of adapting a good stand will be about 

 £& los. or £"] (30s. or £7. for the substage arrangement and £e^ for 

 the lens), or less if a cheaper oil-immersion lens is obtained. 



A mechanical stage is a very great advantage in haematological 

 work, since it enables a preparation to be moved regularly back- 

 ward and forward and up and down, so that all parts of its 

 surface may be examined systematically. A simple form is all 

 that is required, the verniers being quite unnecessary for most 

 purposes. It can be fitted to most stands. Leitz's can be 

 specially recommended. 



Fig. 5. — Hot-air Sterilizer: Simple Form. 



It need scarcely be said that there are many admirable micro- 

 scopes other than those mentioned above, which have simply 

 been selected as favourable and low-priced instruments of English 

 and Continental manufacture. Amongst others, the microscopes 

 made by Beck, Ross, and Watson are all good, and reasonable 

 in price. 



STERILIZATION OF APPARATUS, ETC. 



Requisites. — i. A thermometer graduated to 200° C. 



2. A hot-air sterilizer ; or a cubical biscuit tin, the soldering of 

 which has been replaced by brazing — this must be mounted upon 

 a tripod stand ; or a kitchen oven, preferably a gas oven. 



