326 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
decay. For, in tlie first place, it is now known that nitrifying bacteria 
do not penetrate the soil to a depth of more than three or four feet, and, 
secondly, that granite rocks are often decomposed to depths of more than 
100 feet. 
Bacteria in Ice.* * * § — A bacteriological examination of ice sold in 
Padua, made by Dr. G. Catterina for the purpose of testing its purity, 
showed that there were about 10,000 bacteria per ccm. of the ice water. 
Numerous non-pathogenic water bacteria were isolated, and one organism 
with the biological and morphological characters of B. coli commune. 
In addition to the Schizomycetes, Algae, Protozoa, Vermes, and larvae of 
certain dipterous insects were also observed. 
Bacteriaceae of Bogheads.f — According to M. B. Eenault, Boghead 
coal contains large numbers of micrococci, often difficult to distin- 
guish owing to their smallness and the slight difference between their 
colour and that of the surrounding substance. The cocci are found 
scattered about irregularly in the broken down and disorganised thalli, 
or arranged along the course of the median membranes, the invasion 
having proceeded step by step from the periphery to the centre. 
To the different micrococci of Bogheads the name M. pelrolei is given, 
the varieties being distinguished by the letters A to F. The description 
of the species is Spherical cells measuring from 0*4-0 *5 /x, the walls 
being visible under magnification of 1000-1200 diameters; colourless or 
only faintly coloured, often resembling bright highly refracting spherules 
imbedded in the surrounding medium, or, at a different focus, as hemi- 
spherical cavities of the same diameter. 
Evolution of Mucus in Cancer Ceils. Prof. Quenu and M.Landel 
draw the following interesting and novel conclusions relative to the for- 
mation of pathological mucus, from a histological investigation of a 
u colloid” cancer of the rectum. Two epitheliums of different form and 
origin may co-operate to form a single tumour by the simultaneous pro- 
duction of similar elements. The presence of mucus in cancerous 
elements is not to be regarded as indicative of degeneration, but as a 
normal function of these elements, not lessening their vitality in the 
least. In cancer cells derived from squamous epithelium, the formation 
of mucus is due, not to an alteration or secretion of cytoplasm, but to a 
transformation of the chromatic elements of the nucleus into a substance 
having the characters of mucus. The authors point out that Lukjanow 
had observed precisely the same kind of transformation under normal 
conditions, viz. in the goblet-cells of the intestine of the salamander. 
Plague Bacillus. — Dr. E. Abel § records the results of an exhaustive 
investigation into morphological and cultural characters of the jfiague 
bacillus. In size the bacillus varies from 1 to 4 or 5 /x in length, and is 
about 1 /x broad. In old cultures involution forms are frequent. It is 
quite motionless, and is easily stained with the usual anilin dyes, but not 
by Gram’s method. Neither capsule nor spore formation was observed. 
Cultures were successful in the ordinary fluid and solid media ; the best 
* Aiti Soc. Veneto-Tventina, Padua, iii. (1897) pp. 221-9. 
t Comptes Kendus, cxxiv. (1897) pp. 1315-8. 
X Ann. de Micrograpliie, ix. (1897) pp. 145-65 (3 pis. and 35 figs.). 
§ Centralbl. Bakt. u. Par., l te Abt., xxi. (1897) pp. 497-517. 
