6 BACTERIOLOGICAL DIAGNOSIS. 



gain in magnification brought about by the eye-piece is 

 attended by a loss of definition. The same applies to 

 the increased magnification obtained by pulling out the 

 draw-tube. 



The total cost of a microscope may be put down at 

 1$, and for this sum a thoroughly efficient instrument 

 can be obtained ; while one that will answer every 

 purpose may be bought for decidedly less. The cost of 

 adapting a good stand will be about 6 IDS. or 7 (305. 

 or 2 for the substage arrangement and $ for the lens) 

 or less if a cheaper oil immersion lens is obtained. 



It need scarcely be said that there are many ad- 

 mirable microscopes 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. 



STERILISATION OF APPARATUS, ETC. 



Requisites: i. A thermometer graduated to 200 C. 



2. A hot air steriliser. 



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 been replaced by ' brazing.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. 



3. A steam steriliser. 



or A large kitchen steamer. This should be deep 

 enough to contain a litre flask holding a funnel. 



4. A large Bunsen burner or spirit lamp. 



Bacteria and their spores are ubiquitous, and it is 



