64 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
Nostocaceae.* — Herr P. Kichter prefers the division of the Nosto- 
caceae into Psilonemeae and Trichophoreas, adopted by Thuret and Bornet, 
rather than that proposed by Hansgirg, Bornet, and Flahault, into 
Heterocysteae and Homocysteae ; the presence or absence of heterocysts 
not being of a sufficiently constant character to use for a primary classi- 
fication. He gives reasons for identifying Aphanizomenon incurvum 
specifically with A. flos-aquse, and for regarding Oscillatoria Agardhii as 
a sterile form of the same species. A new species, Aphanizomenon hol- 
saticum , is described. 
Hassallia and Tolypothrix.f — M. M. Gomont proposes the following 
new diagnosis for distinguishing these two genera : — 
Hassallia. Fila fragilia ; articnli diametro trichomatis semper 
breviores. Tolypothrix. Fila flexilia ; articuli diametro longiores, vel 
sub-quadrati. 
£. Schizomycetes. 
Action of Glycerin on the Growth of Bacteria.J— Drs. S. M. 
Copeman and F. K. Blaxall give a preliminary account as to experiments 
on the action of glycerin on the growth of bacteria. The experiments 
had special reference to the bacteriology of small-pox and vaccinia, and 
to the purification and preservation of vaccine lymph. The method 
pursued was to add known quantities of glycerin to tubes of beef-pepton- 
brotli, and subsequently to inoculate these with equal quantities of pure 
cultivation, and incubate at blood-heat and at room-temperature. Control 
inoculations in ordinary beef-broth were invariably made. Inocula- 
tions were afterwards made from the broth-tubes to solid media at vary- 
ing intervals of time, in order to see whether the particular microbe was 
still capable of growth or not. The micro-organisms used were St. py . 
aureus , St. py. albus, Sir. pyogenes, B. pyocyaneus, B. subtilis, B. coli com- 
munis, B. diphtherise, and B. tuberculosis. Small-pox and vaccine material 
in the form of “crusts” and lymph were also used. The results were 
that no visible development took place when more than 30 per cent, of 
glycerin was used. All micro-organisms were killed in it in less than a 
month with 30-40 per cent, of glycerin, except B. coli com. and B. subtilis, 
when kept in the cold. B. coli com., unlike B. typhosus, resists the action 
of 50 per cent, glycerin in the cold for a considerable period, a fact 
which might be used for differentiating these microbes. Small-pox and 
vaccine material are completely sterilised, so far as extraneous microbes 
are concerned, in a week by the presence of 40 per cent, of glycerin in 
the broth- tubes. 
Associated Action of Bacteria.§ — Herren Fesina and Honl think 
that secondary infection and mixed infection should be sharply demar- 
cated. By secondary infection they understand a process wherein a. 
second pathogenic organism, usually a coccus and most frequently strepto- 
coccus, is associated with the first, and, without aiding in the develop- 
ment of the primary process, excites quite independently a second new 
septic condition. Of mixed or multiple generalised infection, some cases 
* Hedwigia, xxxv. (1896) pp. 263-75. 
f Bull. Soc. Bot. France, xliii. (1896) p. 382. $ Proc. Brit. Assoc , 1896. 
§ Intern. Klin. Rundschau, 1891, Nos. 49 and 50. See Centralbl. f. Bakteriol. u. 
Parasitenk., l te Abt., xx. (1896) pp. 689-90. 
