1008 SB'mMARY OF CUltRENT RESEARCHES RELATING TO 



determined that water containing calcium sulphate is not capable of sus- 

 taining the life of Beggiatoa, unless the sulphuric acid is at the same time 

 being reduced to the condition of HgS. 



The granules of sulphur found in greater or less abundance in the 

 filaments of Beggiatoa are not, as stated by Cohn, crystalline, but consist 

 of amorphous masses of the pure element of a soft consistency. It is com- 

 pletely soluble in carbon bisulphide. As soon as the filaments are dead 

 the sulphur at once assumes the crystalline form, large crystals, formed 

 from the contents of several cells, breaking through the cell-walls. 



With regard to the further chemical process which takes place in the 

 filaments of Beggiatoa, Herr Winogradsky came to the conclusion that the 

 sulphur is there subject to a process of oxidation, resulting in the production 

 of sulphuric acid, which, passing into the surrounding water, forms sulphates 

 with evolution of carbonic acid ; and this process goes on very energetically 

 within the filaments. This is regarded by the author as a kind of respira- 

 tion ; though whether it altogether takes the place of the ordinary respira- 

 tion, consisting in the oxidation of carbon compounds, he was unable to 

 determine. This organism appears, at all events, to be able to exist in 

 water which contains but a very small amount of organic matter. The 

 entire removal of sulphur either entirely destroys its life, or possibly 

 induces a resting condition. The source of the sulphuretted hydrogen in 

 the water appears to be the reducing effect on soluble sulphates of the 

 process described by Hoppe-Seyler as the " fermentation " of cellulose. 



Micrococcus ochroleucus.* — Herr 0. Prove finds in human urine a new 

 chromogenous micrococcus, in colonies about 2 mm. in size, at first, and 

 when light is excluded, colourless, but assuming, on exposure to light, a 

 sulphur-yellow colour. The pigment is entirely insoluble in water, but 

 easily soluble in alcohol with a yellow colour. This Micrococcus ochroleucus 

 n. sp. is most easily cultivated on nutrient substances containing a consider- 

 able quantity of albuminoids, and with a slightly alkaline or a neutral 

 reaction ; solid nutrient substances are more favourable than liquid. 

 Carbohydrates alone hinder or prevent the formation of mucilage and of the 

 pigment. Under all these conditions the coccus-form remains unchanged, 

 though the size of the individual micrococci varies. The formation of 

 colonies is to a high degree dependent on the nutriment. In all cases in 

 which there is a considerable separation of mucilage, especially, therefore, 

 when there is abundance of albuminoids, chains of from 8-12 micrococci 

 are produced ; while in those cases where little or no mucilage is formed, or 

 when supplied with carbohydrates only, or in certain saline solutions, the 

 cocci are either isolated or are only associated in small numbers. In the 

 former case it may be termed Streptococcus ochroleucus. The decompositions 

 caused by the microbe vary according to the nutrient substance ; if this is 

 rich in albuminoids, the products are strongly alkaline ; with carbohydrates 

 or certain saline solutions they are, on the other hand, acid. For the 

 production of the pigment abundance of nitrogen is required. A temperature 

 of 36° C. is unfavourable to the vegetative development of the fungus; 

 endogenous resting-spores are then produced, which germinate at 27°. 

 Hard-boiled white of egg made slightly alkaline by dilute ammonia produced 

 the most favourable results. The paper contains also a review of the other 

 known yellow chromogenous microbes. 



Nitrification.t — Sigg. A. Colli and F. Marino-Zuco state that in the 

 course of analyses of water from the subsoil of Eome, amongst other 



* Cohn's Beitr. z. Biol. d. Pflanzen, v. (1887) pp. 409-40 (1 pi.). 



t Gazetta, xvii. pp. 9ij-103. See Journ. Chem. Soc. LoncL, 1887, AbsLr., p. 858. 



