694 SUMMARY OF CURRENT RESEARCHES RELATING TO 



5° C. the process goes on slowly ; at 12° it is clearly perceptible ; at 

 37° it reaches its maximum ; at 55° it ceases. Light is unfavourable 

 to their development. 



The oxidation of the carbon of organic matter is caused in a 

 similar way by minute organisms, and under conditions very similar 

 to those of nitrij&cation. Treatment with vapour of chloroform, the 

 addition of antiseptics such as carbolic or boric acid or thymol, or a 

 high temperature, very materially retard the production of carbon 

 dioxide. Organic substances used as manures decompose more 

 rapidly in well-aerated sandy or gravelly than in close loamy or 

 argillaceous soil. The reduction of the nitrates already formed must 

 be regarded as a physiological process, dependent on the presence of 

 organisms which do not require oxygen, Pasteur's anaerobes. Deprived 

 of air, the organic matters yield small quantities of carbon dioxide, 

 water, ammonia, free nitrogen, and a carbonaceous black peaty mass, 

 an acid humus difficult of decomposition. 



The chemical composition of soils has an important bearing on 

 the decomposition of organic matter ; the presence of lime facilitates 

 it greatly. The amount of humus is also a factor ; the production of 

 carbonic dioxide does not always proceed at so rapid a rate as at first ; 

 and too great a quantity may hinder the activity of the microbes. 



Microbe of Yellow Fever.* — Messrs. D. Freire and Kebourgeon 

 cultivated in bouillon of 38° C. micrococci obtained from the blood 

 of a patient who had died of yellow fever. He found minute hyaline 

 micrococci cells about one-quarter the size of a blood-corpuscle, 

 larger cells of the same kind, and black cells resembling epithelial 

 cells out of which micrococci were produced. Under cultivation the 

 micrococci went through all these stages ; the lowermost layers were 

 blacky and exhibited, like the black cells found in the dejections, the 

 reaction of ptomain. The dead black remains of these organisms act 

 pathogenetically by the formation of ptomain. 



Micro-organisms as a cause of Diphtheria in Man, Pigeons, 

 and Calves.f — For demonstrating the presence of micro-organisms in 

 the diphtheritic process, Herr Lofifler used the following staining 

 solution: — 30 c.c. of a concentrated alcoholic solution of methylen- 

 blue to 100 c.c. of an aqueous solution of caustic potash (1/10,000). 

 It is sufficient to leave sections for only a few minutes in this solution 

 to deeply stain most known bacteria. They are then washed in a 

 1/2 per cent, solution of acetic acid, dehydrated, clarified in cedar 

 oil, and mounted in balsam. 



In twenty-seven cases in which the diphtheritic membrane was ex- 

 amined, two definite species of micro-organism were found — a chain- 

 forming micrococcus and a bacillus. The former was cultivated pure 

 on meat-jelly, blood-serum, and cooked potatoes. It bears a very 

 strong resemblance to the micrococcus of erysipelas, both morpho- 

 logically and as regards its mode of growth, but is only of secondary 

 importance with respect to the diphtheritic process. 



* Comptes Kendus, xcix. (1884) p. 804. 

 t MT. K. Gesimdheitsamte, ii. (1884). 



