278 



Misses M. Stephenson and M. D. Whetham. 



maximum at a point closely corresponding in time to the disappearance of the 

 organic constituents of the medium, and that after this point the lipoids 

 decrease rapidly and the nitrogenous material very slowly. The point of 

 maximum lipoid formation is taken as the stage at which the composition of 

 the organism shall be estimated for purposes of comparison. The results are 

 summarised in the following Table and shown graphically in fig. 2 : — 



Reference 

 to 

 fig. 2. 



Organic constituents 

 of medium. 



{ 



'68 p.c. lactic acid.. 



1 '4 p.c. lactic acid .. 

 1-2 p.c. „ „ . 



4 p.c. acetic acid .. 



1 p.c. glucose 



1 p.c. „ 



1 p.c. acetic acid 



1 p.c. glucose 



2 p.c. „ 



Period of 

 maximum 



lipoid 

 formation 

 in days. 



Grm. in 100 c.c. of medium. 



Ratio : 

 Total lipoid 

 Nitrogen 



Nitrogen 

 ' synthesised 

 by organism. 



Total lipoids 

 formed by 

 organism. 



10 



0-019 



0-016 



-84 



11 



0-026 



020 



0-78 



} ' 



0-020 



0-035 



1 -78 



12 



0-018 



0-028 



1-6 



} « 



0-018 



0-042 



2-34 



15 



0-015 



019 



1-3 



15 



0-034 



021 



0-91 



The results of the two experiments made with lactic acid alone in different 

 amounts, approximate closely in the proportion of lipoid to nitrogen 

 (fig. 2 — 1 and 2). When the organism is grown on a mixture of lactic and acetic 

 acids, no more nitrogen is synthesised than on lactic acid alone, but the lipoid 

 is increased by about 100 per cent. (fig. 2 — 3). A similar effect appears when 



1 2 3 4- 5 O 7 



'68%lac&c iwlaclic hzxlacuc l7<,guicose /Xplucose /7°ylucose zxglucose 

 acid acid acid r/°acelic 

 0-4?. acetic <2<? acid 

 Fig. 2. — Diagram showing the influence of diet on the chemical composition of the Timothy- 

 grass bacillus. 



Black blocks represent grams of nitrogen synthesised per 100 c.c. of medium. Shaded blocks 

 represent grams of lipoid synthesised per 100 c.c. of medium. 



I 



