50 MICRO-ORGANISMS AND DISEASE [chap. 



to 38° C, from some days to one or two weeks, they 

 remain free of any growth. 



Test-tubes containing solid nourishing material are for 

 the purpose of large culture surface, kept sufhciently. 



Fir Q —Tray of Tin used for soLiniFViNG Gelatines or Agar with 

 ^' Slanting Surface. 



inclined during solidification of the material to allow the 

 material to spread into a layer of large area. 



When test-tubes with sterile fluid blood-serum are to be 

 subjected to the process of solidification, it is advisable to 



