ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 637 
The committee are unable to suggest a method of reporting bac- 
terial results, including incubator tests, which is likely to be acceptable 
to all workers. They also make some practical suggestions relative to 
taking samples of sewage for analysis. 
Bacterial Purification of Sewage.* — In his Cantor Lectures Dr. S. 
Rideal took as his theme the purification of sewage by bacteria. The 
earlier portions are historical, and descriptive of the primitive methods 
of disposal of sewage. The different methods and systems of treating 
and getting rid of domestic and manufacturing sewage which were in 
vogue before the biological treatment was adopted, are alluded to and 
described in turn. The greater part of the discourses is reserved for 
bacteria and thdir work, and it is shown that any system for the disposal 
of sewage, to be effective, must be based on the alternate action of 
anaerobic and aerobic bacteria. For in this way almost all the sludge 
is caused to disappear as gas, and the filtrate rendered comparatively 
innocuous. The lectures contain a large number of facts bearing 
directly and indirectly on the subject of sewage and sewerage. 
Fermentation of Malic Acid by Bacteria.! — Herr O. Emmerling 
isolated from a solution of malic acid, in which fermentation had been 
induced by inoculation with one drop of putrefying flesh, Bacillus lactis 
aerogenes. This bacillus, first discovered by Escherich in the intestines 
of sucklings, is a short thick non-motile bacillus, and was identified by 
the form of its colonies, the milky white appearance of the gelatin 
culture, the absence of spores, and by decolorising by Gram’s method. 
In a solution of bouillon and sugar it developes hydrogen and carbonic 
anhydride in molecular proportion. The pure culture acts on malic 
acid, reducing it to succinic acid, almost quantitatively according to the 
equation 3C 4 H 6 0 5 = 2C 4 H 6 0 4 -f- C 2 H 4 0 2 -f- 2C0 2 -}- H 2 Q. Alcohol is 
not produced, but traces of formic acid can be detected. The conversion 
of malic acid into succinic acid by brewer’s yeast is due to bacteria, and 
does not take place with pure cultures. Konig has shown that tartaric 
acid is largely reduced to succinic acid by B. termo , but B. lactis aero- 
genes appears to cause decomposition in other directions. 
Movement of Bacilli in Liquid Suspension on Passage of a Con- 
stant Current. J — Dr. A. F. Bill passed a constant current through 
suspensions of various micro-organisms. On closure of the current a 
movement set in towards the positive pole, while at a lower level there 
was a reverse stream towards the negative pole. Two exceptions were 
found : — (1) in 1 per cent, pepton where the current was delayed or 
never set in ; (2) in bouillon the course of the currents was reversed. 
Experiments with unorganised and finely powdered substances pro- 
duced the same results, and the observations suggest that the movements 
towards one or other pole are of a physical nature ; that they are not 
physiological or galvanotropic. 
Three new Lactic Acid Bacteria.§ — Herr E. Weiss describes three 
new bacteria which were isolated from the juice of turnips. The 
* Journ. Soc. Arts, xlvii. (1899) pp. 683-9, 695-703, 707-17, 719-30 (6 figs.). 
t Ber. Deutscli. Ckem. Gesell., xxxii. (1899) pp. 1915-8. See Joum. Chem. Soc 
lxxv. and lxxvi. (1899) Abst., ii. pp. 569-70. 
X Centralbl. Bakt. u. Par., l te Abt., xxvi. (1899) pp. 257-9. 
§ Joum. f. Landwirthschaft, xlvii. (1899) p. 141. See Centralbl. Bakt. u. Par. 
2“ Abt., v. (1899) pp. 599-601. 
1899 2 u 
