ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
237 
which together, but not singly, dccompos3 nitrites with liberation of free 
nitrogen. One was identified as B. coli commune , whilst the new one 
was designated B. denitrificans i. Another variety, B. denitrijicans ii., 
which liberates nitrogen from nitrates and nitrites, was isolated from old 
straw. This microbe throve in artificial solutions as well as in nitrate- 
broth, and destroyed the nitrate in the same length of time. B. coli 
with B. denit . i. caused no turbidity in the artificial solution in a week, 
and did not decompose the nitrate in the least. With B. coli and 
B. denit. i., and also with B. denit . ii., the destruction of nitrate is checked 
when the amount of nitrate exceeds 0 * 5-0 • 6 per cent., owing to excessive 
alkalinity. Phosphoric acid (0*06-0 *07 per cent.) checked the fermen- 
tation by B. coli and B. denit. i. ; whilst B. denit. ii. was active with 
0*14 per cent, of acid. B. denit. i. and B. coli reduce nitrates com- 
pletely in the absence of oxygen, but without evolution of nitrogen, the 
nitrate being converted into nitrite. But with even a limited access 
of air these organisms will produce free nitrogen. B. denit. ii. decom- 
poses nitrates normally in complete absence of air ; whilst with aeration 
the fermentation is hindered or prevented. 
Inoculation of Nodule-Bacteria in different Host-Species.* — Herren 
F. Nobbe and L. Hiltner have carried on a series of experiments on the 
inoculation of bacteria from the root-tubercles of one to those of a dif- 
ferent species. The results were, as a rule, negative, the inoculation 
being certain only from one plant to another of the same species. An 
exception is afforded by the Yicieae, where inoculation, without essen- 
tially lessened effect, is possible from one species to another. The effect 
of inoculation was increased vigour and development cf the plant ; in- 
creased production of flower and fruit was observed, especially in the 
case of peas and red clover. The authors state that root-tubercles have 
no essential influence on the growth above ground, so long as the soil 
contains sufficient nitrogen. 
Bacterial Diseases of Plants.f — Mr. E. F. Smith gives a resume of 
the diseases of plants ascertained to be due primarily to the attacks of 
Schizomycetes, arranged according to the host-plant which they attack. 
Five of these belong to the beet aud two to the hyacinth. The bacterial 
disease of the potato is referred to an unnamed organism (Kramer’s 
potato bacillus), which differs from both Bacillus amylobacter and 
B. butyricus in not being anaerobic. 
Bacteriosis of Celery. :J — Dr. Ugo Brizi describes a disease which 
affected the celery plants in North Italy in the past year. The parts of 
the plant (Apium graveolens) most attacked were the stems, which first 
showed the malady, presenting yellow to brownish spots, which after- 
wards ulcerated. Microscopical examination showed the presence of a 
large bacillus ( Bacterium Apii), which was easily cultivated on various 
media. 
Bacterial Disease of the Squash-Bug.§ — Mr. B. M. Duggar found 
that squash-bugs ( Anasa tristis), kept for laboratory purposes, died in 
* Landwirth. Vers.-Stat., xlvii. (1896) pp. 257-68. See Journ. Chem. Soc., 1897, 
Abstr., p. 61. 
f American Naturalist, xxx. (1896) pp. 626-43, 716-30, 796-804, 912-24; xxxi. 
(1897) pp. 34-41, 123-38. % Atti R. Accad. Lincei, vi. (1897) pp. 227-34. 
§ Bull. Illinois State Laboratory Nat. Hist , iv. (1896) pp. 340-79 (2 pis.). 
