CONDITIONS OF LIFE OF THE FISSION FUNGI. 529 



that form of tartaric acid which turns the polarisation to 

 the right which can he taken up by hacteria. 



In the case of some hacteria, the most favourable 

 nutrient conditions have been more accurately deter- 

 mined ; for example, by von Jacksch* for micrococcus 

 urea, and by Hueppe t for the lactic acid bacilli. Micro- Nutrient 

 coccus ureae can, for example, obtain the necessary e *e/sary for 

 nitrogen and carbon from nutrient solutions containing coccus 

 succinate, lactate, malate, tartrate, or citrate of ammonia, 

 from glycocoll, leucine, asparagine, salts of asparagine, 

 creatine, benzoate of ammonia, hippurates, and peptone. 

 On the other hand, the following were useless as sources 

 of nitrogen and carbon : formate, acetate, butyrate, 

 oxalate, and salicylate of ammonia, and acetamide. 



In the case of bacterium lactis, carbon is best obtained For bacterium 

 from milk sugar, cane sugar, mannite, and dextran ; 

 the best source of nitrogen was peptone, or among the 

 salts, tartrate of ammonia. Nitrates were quite unsuit- 

 able as sources of nitrogen. The most favourable pro- 

 portion of the nutrient salts was 0*2 0'5 per cent, of 

 acid phosphate of potash, + 0'05 to O'l per cent, of 

 sulphate of magnesium -4- 0'015 0'025 per cent, of 

 chloride of calcium ; this mixture could be replaced by 

 1 per cent, of extract of meat. 



These numbers are, however, only applicable to these Difference as 

 special cases. The more accurately the various species nuSient^e- 

 of bacteria have been studied during the last few years, quirements of 



* . . '' ' the different 



the more have differences in the nutrient requirements species of 

 of the different species been observed. Some require bact 

 large quantities of certain albuminoid substances, and 

 only permit a variation in the composition of the nutrient 

 material within very narrow limits ; others permit a 

 greater variation in the nutrient materials, which, how- 

 ever, must be fairly concentrated and composed of 

 complex molecules. Others, finally, prefer very dilute 

 and simple solutions in which one can scarcely recog- 

 nise anything of nutrient value. Among the bacteria Contrast 

 which are most sensitive in this respect are chiefly the ^t^o^nic 16 



bacteria and 



* Zeitschr.f. physiol. Chem., vol. 5. J 



f Mitth. a. d. Kais. Ges., vol. ii. water 



34 



