CHAPTER VI. 



CULTIVATIONS AT HIGHER TEMPEEATUEES. 



Thekb are a great many bacteria, whioli at the ordi- 

 nary temperature of a room can either only develop 

 slowly, or not at all, and it is therefore necessary, in 

 order to become thoroughly acquainted with their 

 peculiarities and characteristics, to cultivate them at a 

 higher temperature — as a rule at blood heat. Amongst 

 the different forms which have made their appearance 

 so far upon our plates, probably there would be some 

 of one kind or another, which only develop slowly at 

 ordinary temperatures, but which flourish well at some- 

 what higher ones, from 20°-2o° C. Above all, patho- 

 genic bacteria, which without exception flourish better 

 at higher temperatures, must be cultivated at blood 

 heat. 



In order to keep these cultures at as even a 

 temperature as possible, use is made of an incubator, 

 which is a tin box with double walls, covered outside 

 with felt. The simplest form, which is quite sufficient 

 for our needs, is a square box, whose top can be re- 

 moved and used as a lid, and between the double walls 



