THE CULTIVATION OF BACTERIA. 



95 



semi-solid consistency, and does not retract at the edges on cooling. 

 The paraffin prevents the absorption of oxygen, except to a small 

 extent at the edges. The method is useful for large quantities of cul- 

 ture material, as in flasks. Esmarch advised making roll-tubes, and 

 after cooling them to fill them with a liquefied gelatin cooled down 



FIG. 29. 



An Aerobic Organism (Potato Bacillus) which will not grow under a 



cover-glass. 



to near the point of solidification. Hueppe made use of eggs in their 

 shells. The eggshell was carefully cleaned, sterilized with a solution 

 of bichloride of mercury, washed with sterilized water and wiped dry 

 with sterilized cotton. The end of the eggshell was punctured with a 

 hot needle. Through the opening thus made the inoculation was accom- 

 plished. The opening was closed with collodion. 



