570 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
excreted by the bacteria. The process is not a vital one. Tbe substances 
contained in an alcoholic extract appear to have, though to a less extent, 
the same power of occluding oxygen, though this property is soon lost. 
The purple and green bacteria, in which the pigment forms an integral 
part of the bacterial plasma, show, when exposed to radiant energy, a 
very weak evolution of oxygen, continuing for an indefinite length of 
time if conditions are favourable. In the former of these the assimilat- 
ing pigment is bacterio-purpurin, in the latter chlorophyll. The pro- 
cess is a vital one, and the oxygen evolved is apparently derived from 
the assimilation of carbon dioxide.” 
Ferrophilous Bacteria.* — Herr G.Marpmann describes an iron bac- 
terium, which was isolated on silk-jelly. The rodlets, which are motion- 
less and devoid of cilia, are from 2-3 /x long and 0 • 8-1 /x broad. The ends 
are rounded, and there are polar black chromatophores with intervening 
grey granules. Many of the cells are black throughout. The pigment, 
which is insoluble in alcohol, ether, bisulphide of carbon, and benzin, 
contains both sulphur and iron. When cultivated on pepton-gelatin, the 
colonies were colourless, and did not give the iron reaction. Hence 
the iron must have been selected from the medium and assimilated by 
the bacteria. 
Root-Tubercle and other Bacteria in their Relation to Vegetable 
Tissue.j" — The chief results of the experiments made by Herr 0. Zinsser 
to determine more closely the relation of root-tubercle and other bacteria 
to living vegetable tissue, were that there is no hereditary infection of 
the seeds of Leguminosee ; for when cultivated under sterile conditions 
Leguminosae are devoid of root-tubercle. The bacteria are not to be 
met with in the internal parts of the rootlets, nor in the portions of the 
plant above the earth ; and even when artificially introduced they seem 
neither to wander very far from the inoculation site, nor to live very 
long. Other kinds of bacteria seem to behave in very much the same 
way towards healthy plants. The root-tubercle bacilli do not appear 
able to form nitrogenous compounds necessary for their existence, by 
assimilation of free nitrogen. Besides the mere presence of rhizobes, 
certain associated conditions are necessary for the development of root- 
tubercles. 
Sensitiveness of Frogs to Infection with Plague. J — Herr D. V. 
Devell states that frogs ( Hana temporaria) are sensitive to the virus of 
plague, both in summer and in winter. They may be infected by the 
introduction of cultures, or bits of organs of animals affected with 
plague, into the lymph-sac. Spontaneous infection of frogs may occur 
if the skin be wounded. From infection with bacilli of constant viru- 
lence for white mice (death in 2-2^ days), frogs die of plague in from 
13-19 days. After one passage through the frog, the plague bacilli kill 
frogs in 12-14 days, after a second passage in 7-8 days, and after a 
third in 5 days. 
Antivenomous and Antitoxic Qualities of the Bile of Serpents 
and of other Animals.§ — Prof. Fraser has shown that the bile of certain 
* Centralbl. Bakt. u. Par., l te Abt., xxii. (1897) pp. 124-7. 
+ Jahrb. f. wiss. Bot. (Pfeffer u. Strasburger), xxx. (1897) pp. 423-52. 
X Centralbl. Bakt. u. Par., l te Abt., xxii. (1897) pp. 382-5. 
§ Brit. Med. Journ., 1897, ii. p. 595. 
