ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 457 



which was to accumulate that variety of bacteria in a mixture which was 

 best adapted to the conditions of the experiment. In some cases the 

 experiments resulted only in the relative increase of one variety, whilst 

 in others one variety accumulated and the rest completely disappeared. 

 Bacteria which decompose carbamide are of two kinds, one effecting 

 decomposition by means of urease, an enzyme insoluble in water, and 

 the other (a phosphorescent species) by direct contact with the living 

 protoplasm (katabolism). These two methods of decomposing carbamide 

 are distinguished by the temperature at which the maximum decom- 

 position takes place, the katabolic decomposition being at its maximum 

 at the most favourable temperature for the growth of the micro-organisms, 

 whilst the decomposition produced by urease is at its maximum at a much 

 higher temperature. 



Bactericidal Properties of Blood Serum.* — Dr. Ostrianine made 

 experiments on the bactericidal effect of rabbit serum on anthrax and 

 cholera under normal conditions and during the infection from these 

 organisms. The conclusions arrived at were that the bactericidal pro- 

 perty of the serum of rabbits infected with anthrax and cholera is not 

 exhausted during the disease, and that it is related to the leucocytosis. 



* Ann. Inst. Pasteur, xv. (1901) pp. 266-7S 



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