102 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
culture is more resistant than a younger one, and that individuals of the 
same culture betray like differences ; some live while others die, though 
under exactly the same conditions. 
The characters of some species ( coli , typhoid) are altered by the 
action of high temperatures. Some species become accustomed to the 
action of antiseptics, if these be added gradually. The tubercle bacillus 
can be much better cultivated on gelatin if previously it have been 
bred for some time on blood-serum. All these phenomena indicate that 
the biological characters of the same species are often very unlike at 
different times or under different conditions. 
Variations of pathogenic properties of the same species are very 
important. It is usual for each species to exhibit its most virulent 
characters towards certain kinds of animals, e. g. as does anthrax. But 
even for the same kind of animal the virulence may be stronger or 
weaker, and hence it was that Pasteur was able to diminish the virulence 
of anthrax, and conversely to increase the virulence. 
Cultivated in the laboratory the cholera vibrio gradually loses 
its virulence. Blackstein, however, found the virulence increase in 
gelatin containing phosphates or a trace of iron. Vibrios, coli and 
typhoid bacteria are most virulent immediately after their exit from the 
body. 
The author believes that Bac. coli is the actual cause of typhoid, 
because in water typhoid bacteria are rarely found, while coli bacteria 
are frequent ; and also because in the dejecta of typhoid patients the coli 
bacteria are frequent, while the typhoid bacteria are scanty. Indeed, it 
would seem from the frequent references to B. coli and B. typhosus that 
the author’s main object is to prove the identity of the two organisms. 
Species of Sarcina.* — In the introduction to his paper Herr Th. 
Gruber gives a short history of the genus, and explains the principle of 
his classification. A cellulose membrane cannot be demonstrated. 
Altogether, 39 species are known, of which 19 have been recently 
described. The special part of the work deals with the morphological 
and biological characters of the different species. The following table, 
to facilitate the recognition of the species, is given at the end : — 
I. Species, the Colonies of which are White in Solid Media. 
1. Forming typical packets in solid and liquid media. 
a. Gelatin liquefied, 
a. Colonies round. 
S. alba Zimm., S. alutacea sp. n. 
(3. Colonies of irregular shape. 
S. incan i n. sp. 
b. Gelatin not liquefied, 
a. Colonies round. 
S. pulchra H enrici. 
(3. Colonies of irregular shape. 
S. pulmonum Virch., S. lactea sp. n., S. vermicularis sp. n., 
S. minuta De By., sp. n. 
* Arb. a. d. Bacteriol. Inst. d. Techa. Hocksch. zu Karlsruhe, i. (1895) p. 239. 
See Hedwigia, xxxiv. (1895) Rep., pp. 72-3. 
