344 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
may have stamped on it sucli differences that its plate-colonies differ 
considerably at different times of the year, or even in the same season,, 
according to the length of time the individual germ isolated has been 
in the river. (3) It is in great part owing to the coincidence of these 
causes of variation that it is often so difficult to recognise a given 
“ species ” ; in fact, the same “ species ” recurs under different names,, 
because the conditions preceding and during its cultivation in the 
laboratory have differed more or less. 
Fossil Bacteria.* — In addition to species already described, M. B. 
Renault now records the following from coprolites and schists in the 
neighbourhood of Autun -.—-Bacillus permiensis (previously described 
as Bacterium permiense ), 12-13 X 1*3-1 *5 /x; Bacillus granosus, 9-10 
X 1*6 fi, often united into filaments, and apparently containing spores ; 
Micrococcus lepidophagus and Bacillus lepidophagus , closely resembling 
existing bacilli of the caries of teeth ; Bacillus Tieghemi , in the pith of 
Artliropitijs lineata , near to B. Amylobacter ; Micrococcus priscus and M. 
esnolensis, respectively 0*6 x 0*7 /x and 2*5 x 3*4 /x, from the Culm. 
Root-Tubercle Bacteria of Leguminosse.f — Prof. Stutzer discusses 
the more recent views respecting the root-tubercles of Leguminosae, and 
the part played by micro-organisms in the fixation of free nitrogen. 
Nobbe showed that the bacteroids of all the Leguminosae, even of the 
Mimosese, belonged to one species, Bacillus radicicola. This, however, 
is so much influenced by the plant on the roots of which it lives, that 
its descendants become adapted only to that species of Leguminosae to 
which the host-plant belongs, and for all the rest losing more or less its 
special property. The neutral root-tubercle bacteria are found only in 
soil which for a long time has not borne Leguminosae. How the free 
atmospheric nitrogen is made to unite with hydrogen and oxygen 
through the intermediation of bacteroids is chemically an unsolved 
question. 
Root-tubercles are occasionally observed on non-leguminous plants, 
such as Elseagnus, Hippophae, and Alnus ; but the organisms are quite 
different. The question whether for the fixation of free nitrogen by the 
higher chlorophyllous plants the symbiosis-fungus of the Leguminosae 
is absolutely necessary, or whether the atmospheric nitrogen can be 
assimilated by those chlorophyllous plants which do not form tubercles, 
has been answered in opposite ways by different investigators. Still, it 
is thoroughly well made out that in the soil there exist micro-organisms 
which are able to fix free nitrogen. 
False Bacterium/]; — Prof. H. M. Ward isolated an organism which 
forms non-liquefying porcelain-white or cream-coloured colonies on 
gelatin, and behaves like a Schizomycete on other media. It does not 
ferment glucose ; under the Microscope its form is bacilloid, 2-4 /x 
long and 1 fx thick, or coccoid, 1 /x in diameter. It stains by Gram’s 
method, is devoid of movement and of endogenous spores. On alkaline 
gelatin, and observed under high powers, it is found to branch and to 
* Bull. Soc. d’Hist. Nat. Autun, vii. (1895) pp. 433-68. See Bull. Soc. Bot. 
France, xlii. (1895) p. 676. Cf. this Journal, 1895, p. 467. 
f Centralbl. f. Bakteriol. u. Parasitenk., 2 te Abt., i. (1895) pp. 68-74. Cf. this 
Journal, 1895, p. 566. % Ann. Bot., ix. (1895) pp. 657-8. 
