316 SUMMARY OF CURRENT RESEARCHES RELATING TO 



unsuitable media, and in their sensitiveness to acid reacting media. 

 From both tbey differ in their dislike to nitrogen compounds such as 

 pepton, gelatin, and broth. Hence this kyphomicrobe takes a separate 

 position intermediate between bacteria and Hyphomycetes. 



The authors pursue the subject of the morphology and physiology 

 of the nitre microbe,* and come to the following conclusions. The 

 nitre microbe is not a bacterium, but has a separate position among 

 micro-organisms. It oxidises nitrite to nitrate. Besides nitrates it can 

 use as nutriment ammonia compounds and nitrates, but not the complex 

 organic nitrogen compounds such as pepton, &c. It can profit by free 

 atmospheric carbonic acid, but not by the combined carbonic acid of 

 alkalis and of the alkaline earths or the organic carbon compounds such 

 as sugar. The nitre microbe obtains the necessary energy for the 

 formation of organic substances out of inorganic materials, partly 

 chemosynthetically by the oxidationiof nitrites to nitrates, and possibly 

 also thermosynthetically by turning heat to account. 



Bactericidal Power of the Blood.t — Prof. A. E. Wright, in a second 

 communication on the quantitative estimation of the bactericidal power 

 of the blood, thus summarises his conclusions. What is measured by 

 the gelatin method is rather the total antibacterial power of the blood 

 than the bactericidal power proper. To determine how much of the 

 result which is registered is referable to an inhibition of the growth 

 of the bacteria, and how much to a direct bactericidal action, it is neces- 

 sary, after the cultivation tubes have been incubated and examined micro- 

 scopically, to melt down the gelatin and to blow out the contents of the 

 tabes into sterile nutrient broth. Where it is desired separately to 

 estimate the bactericidal power, this can readily be done by making a 

 series of graduated dilutions of a bacterial cultivation in broth and by 

 mixing one volume of each of these with one volume of undiluted serum. 

 This method may appropriately be employed when dealing with bacteria 

 such as the cholera vibrio or the typhoid and diphtheria bacilli, which 

 are readily killed off by the normal human blood. When the last 

 method is employed and when the bacteria have been counted, a con- 

 venient arithmetical expression for the bactericidal power is obtained 

 by specifying the number of organisms which one cubic millimetre of 

 serum is capable of killing. When bacteria are not killed off, or only 

 in small numbers, by normal human blood, or when the blood has lost 

 much of its bactericidal power, the gelatin method may appropriately 

 come into application. 



Soluble Ferment in Cultures of Bacillus Tuberculosis.^: — Dr. G. 

 Carriere finds that there exists in cultures of B. tuberculosis a soluble 

 ferment which decomposes monobutyrine. It is analogous to and per- 

 haps identical with the lipase described by Hanriot. Its activity varies 

 with the age of the culture. There is no constant relation between the 

 amount of the ferment and the virulence of the culture. 



Pathogenic Microbes in Milk. § — Dr. E. Klein, who has examined 

 a large number of samples of milk and secretions of diseased udders, 



* Tom. cit., pp. 197-232. See Beih. z. Bot. Centralbl., ix. (1900) p. 544. 

 t Lancet, 1901, i. pp. (309-12. Cf. this Journal, ante, p. 97. 

 I C.R. Boc. <ie Biol, de Paris, liii. (1901) pp. 320-2. 

 § Journ. Hygiene, i. (1901) pp. 78-95. 



