View report page

16
Five litres incubated in agar-agar at 37° C. yielded 5 colonies, all of which were
bacterial.
The following species were identified in this 10 litres of air—Micrococci: Sarcina alba
lutea and flava, staphylococcus cereus flavus, M. candicans, M. flavus, M. lactis. Bacilli: B.
subtilis, B. raesentericus fuscus, B. mesentericus ruber, B. luteus, B. arborescens,- B. lactis
innocuus, and an undetermined bacillus. Yeast: Torula alba. Moulds: Penicillium
glaucum, and an allied species.
Fresh air—Five litres incubated in gelatin at 20° C. yielded 13 colonies, viz., 10 bacterial
colonies, 1 yeast and 2 moulds.
Five litres incubated in agar-agar at 37° C. yielded not a single colony ot any sort.
The following species were identified in this 10 litres of air—Micrococci: Sarcina lutea
and flava, with an undetermined species of coccus. Bacilli: B. fulvus, B. subochraceus,
B. arborescens, and B. aeris minutissimus. Yeast: Torula rosea. Moulds: Aspergillus
glaucus and a species of mucor.
XII.—On June 19th samples were taken at 11 a.m. in a branch passage near the foot of the
stairs at the Post Office station. There was no direct traffic past the apparatus, but passengers were
passing to the lifts within 20 feet, and a moderate current of air was passing from them to us. The
temperature was 68° F., and the barometer 30 in. The percentage of carbon dioxide in the air was *102 ;
the organic matter was .0023. Fresh air samples were then taken on a scaffold above the station in
Newgate-street, about on a level with the top storeys of the adjacent houses, and well above the
ordinary street traffic. It was a bright, sunny day and dry. No rain had fallen for two days, and
there was a moderate S.E. wind. Temperature, 69° F. ; barometer, 29.86 in. The carbon dioxide in
the air was .041 per cent., and the organic matter was .0021.
The results were as follows—
Passage air.—Five litres incubated in gelatin at 20° C. yielded 24 colonies, of which
17 were bacteria, 2 yeasts and 5 moulds.
Five litres incubated in agar-agar at 37°. C. yielded 5 colonies, of which 1 was a
streptothrix and the rest bacteria.
The following species were identified from this 10 litres of air—Micrococci: Sarcina
lutea, and an undetermined species of sarcina, staphylococcus pyogenes albus, staphylococcus
cereus albus, M. cremoides, M. concentricus, M. orbicularis, M. flavus, M. albicans tardissimus,
and diplococcus citreus conglomeratus. Bacilli: B. pyocyaneus, and two bacilli
which I could not identify. Yeasts: Torula alba and torula rosea. Streptothrix: Str.
chromogenes. Moulds: Penicillium glaucum and an allied species, aspergillus glaucus and
aspergillus fumigatus, with a mould belonging to an undetermined genus.
Fresh air.—Five litres incubated in gelatin at 20° C. yielded 44 colonies, of which 23
were bacteria, 3 yeasts, and 18 moulds.
Five litres incubated in agar-agar at 37° C. yielded 8 colonies, all of which were
bacterial.
The following species were identified in this 10 litres of air—Micrococci: Sarcina alba,
a species of streptococcus, staphylococcus cereus flavus and albus, M. cremoides, M. flavus,
M. albicans tardissimus, M. aurantiacus, M. citreus and diploccocus citreus conglomeratus.
Bacilli: B. helvolus, B. subochraceus, B. latericius, B. aeris minutissimus, B. fulvus, B.
arborescens, B. mesentericus ruber or an allied species, and three bacilli which I was unable
to identify. Yeasts: Torala alba liquefaciens, and a species of oidium. Moulds : Penicillium
glaucum, aspergillus glaucus, and several forms, the genera of which I could not determine.
This concludes the detailed record of the experiments. Before tabulating and discussing the
results, I will describe the two abortive experiments in which I endeavoured to demonstrate the
presence of anaerobic bacilli in the air of the Central London Railway.
XIII.—On May 23rd, 10 litres of air were aspirated through a tube such as I ordinarily used,
in a smoking carriage in the rear of a train as we travelled between Holland-park and Lancaster-gate
stations. There were plenty of passengers, but the carriage was not crowded. The glass-wool and
sugar plug was placed in a broth tube containing 2 per cent, of glucose, and incubated anaerobically
at 37° C. for 3 days. It was then examined, but no micro-organisms could be found microscopically.
An aerobic subculture on agar-agar yielded a single colony of an aerobic sporing bacillus. The
original culture was then further incubated aerobically and became turbid with the growth of a motile
sporing bacillus.
XIV.—On May 27th, 10 litres of air were similarly aspirated, on the up platform of the Bank
station at 11.10 a.m. Very few people were on the platform. The plug was treated as in the
preceding experiment and yielded no growth at all. After 4 days, subcultures were made aerobically
on agar-agar and anaerobically as a stab culture in glucose gelatin. No growth occurred in either.
The original culture was then further incubated under aerobic conditions, but no growth occurred.
There was thus no evidence at all of the presence of strictly anaerobic bacilli in these two
experiments.
I will now endeavour to classify and tabulate the results of the twelve observations, in order
that they may be rendered more intelligible. I will deal first with the total number of organisms
found in the different samples examined, irrespective of the species to which they belong.