ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
695 
chloric) or alum in various degrees of concentration. The cultivations 
were made in test-tubes at temperatures varying from 16 0 -23°. 
The results, carefully tabulated and recorded, amount to this, that a large 
number of bacteria grow on acid media, some indeed very well, provided 
that a certain degree of acidity be not exceeded. The maximum acidity 
of the medium was found to vary extremely for each different species. 
The only Schizomycete which would not grow at all on any acidified 
medium was the micrococcus of erysipelas, while the Bacillus anthracis 
grew even when the medium contained 0*2 per cent, of lactic acid, and 
with 0*2 per cent, of alum its growth was better and more rapid than 
on neutral media. Nor was the virulence of the anthrax diminished, as 
was proved by inoculation experiments on mice. 
It would appear that the biological characteristics of some fission 
fungi are brought out very clearly on acid media ; among these may be 
mentioned the bacillus of typhoid and the bacillus of blue milk ; the 
latter grown on isinglass decoction, to which 0 * 2 per cent, of lactic acid 
had been added, developed its well-known pale blue hue, a phenomenon 
which does not occur on alkaline substrata. 
Pure Cultivation Methods and Specially Koch’s Plate Cultivation 
and the Limit of Error of this Method.* — In the first part of his 
article Herr J. C. Holm passes in review the history of pure cultivation 
methods and points out that pure cultivations may serve two different 
ends, viz. for examining the morphology of a micro-organism and for 
making physiological experiments with it. 
The second part is an experimental study on the limits of error in 
Koch’s plate cultivation method, though in reality it only deals with 
the problem of how many pure cultivations arising from a single cell can 
be obtained by isolating yeast cells on gelatin plates, bacteria being left 
out of consideration altogether. 
The third part deals with the numerical variability of yeast cells 
capable of developing in wort gelatin, according as these cells are taken 
at the beginning or end of the fermentation process, and also discusses 
the gelatin media suitable for yeast cells. It is here stated that 4 * 5 per 
cent, of the yeast at the beginning and 25 * 5 per cent, of that at the end 
of the fermentation process is incapable of development, and that gelatin 
made up with beer wort gives the best results. 
Preparing Catgut. | — Herr Braatz has made some experiments for 
the purpose of showing how fat prevents disinfection. Pieces of catgut 
1-1^ cm. long were sterilized in dry heat of 140° for 3 hours; these 
were then infected with fresh anthrax spores and preserved dry. He 
then succeeded in showing that oil had a detrimental effect in disinfect- 
ing with sublimate solution. 
Hence if catgut is to be effectually disinfected it must be deprived of 
fat, and this is best done by means of ether, and after this, treatment 
with sublimate is the best procedure. 
The author further made some experiments as to the sterilization 
* CR. des Travaux du Laboratoire de Carlsberg, iii. (1891) pp. 1-23. See 
Centralbl. f. Bakteriol. u. Parasitenk., xi. (1892) pp. 576-7. 
t Bran’s Beitrage zur Chirurgie, vii. (1891) No. 1. See Centralbl. f. Bakteriol. 
u. Parasitenk., xi. (1892) pp. 627-8. 
