'rfiE cuLTivATioisr OF' Micro-organisms 



IIS 



may not melt the gelatin. Agar roll-tubes should be kept in a 

 position a little inclined from the horizontal, with the neck up, 



Pig. 4S.— Dilution-cultures in Esmarch roll-tubes. In tube i the colonies are 

 very close together; in tube 2 they are somewhat separate; in tube 3 they are well 

 isolated. ' 



for twenty-four hours, so that the agar may adhere to the wall 

 of the tube. 



