82 ATLAS OF BACTERIOLOGY. 



XIII., 70; XVI., 150; and XXII., 167). The fol- 

 lowing statements and figures must suffice for the 

 limits of this work. 



The amount of water in a culture which has grown 

 upon a solid nutrient medium, and likewise the 

 amount of ash, depend in a very great measure upon 

 the composition of the nutrient medium. 



For example, bacterium prodigiosum contains, 

 when cultivated on potato, 21.49 per cent dry sub- 

 stance, 2.70 per cent ash in the fresh substance; 

 when cultivated on carrots, 12.58 per cent dry sub- 

 stance, 1.31 per cent ash in the fresh substance. 



Apart from the concentration of the nutrient me- 

 dium, higher temperatures and youth of the cultures 

 increase the amount of dry substance and ash. 



The amount of dry substance of bacteria also varies 

 in its composition in the same variety, under the in- 

 fluence of the nutrient medium. 



For example, the bacterium pneumonise Fried. , upon 

 a nutrient medium of meat-infusion agar, contained : 



With 1 per With 5 per 

 cent peptone, cent peptone. 



Albumin 71.7 79.8 



Ether and alcoholic extract 10. 3 11. 28 



Ash 13.94 10.36 







and with one per cent peptone and five per cent grape 

 sugar : 



Per cent. 



Albumin 63. 6 



Ether and alcoholic extract 22. 7 



Ash 7. 88 



It is evident that an increase in the amount of pep- 

 tone in the nutrient medium causes an increased 



