32 Itnrlrrin 'in lii-lnlinn l<> ('oiinlri/ Lijc 



injured <r suppressed by rompara! i vel y slight amount:; 

 of . U":ir, :in<l I IK- failure of putrefying organisms to 

 develop in milk under ordin:iry eoudil ions is ascribed 

 directly or indirectly to the influence of UK; milk-sugar. 

 The range of carbon compounds used by bacteria as a 



source of food is very large. Grape-sugar, cane-sugar, 



milk-sugar, iu;ilt-su^jir, and m;umite, a coinpoiunl 

 c|o:;ely re|;i!cd fo Uie sugars, :ire I'e.-idily used by ni;iny 

 organiwrilS, :i. :ire :d: :c :;iidi com poii m Is MS slitrch, dex- 

 trin and cellulose, capable of being changed into sugar. 



The conijHHindN oj carlion in haclcrid. 'IMi(; eiu'i'gy 

 stored up in those substances is employed for the; manu- 

 facture of the compounds found in the bacterial body. 



In older words, the bacteria burn up the sugars :md 

 allied in.'il eri:ils in ;i ninnner :iii:dogous to tin; burning 

 up of I he food in the animal body. 



The c:irbon compounds eimmer.-iled consist of I luce 

 chemicnl elements rarbou, hydnigen, and oxygen. 

 There are, however, still other classes of carbon com- 

 pounds soi/ed upon with even greater avidity by im- 

 portant' groups of bacteria. The compounds in question 

 are (ho proteins composed of carbon, nitrogen, hydro- 

 gen, oxygon, and sulfur, and substances derived from 

 the prolein.; and composed of carbon, nitrogen, hydro- 

 gen and oxygen. The numerous species ol dec.-iv and 

 put refaction - bad ena are especially favored in I heir 

 development, by protein compounds and grow rapidly 

 in meat and meal exlracls, e"", albumin, and other 

 materials of animal or vegetable origin, rich in protein. 

 Kor this reason, beef broth, supplemented by mineral 

 salts, is n;:ed almost universally in bacteriological labora 



