170 THE AMERICAN MONTHLY [September, 
articles were heated enough, they were allowed to remain until the cotton in 
the necks of the bottles was discolored by the heat. 
For sterilizing culture media, the tubes containing them were placed in 
boiling water, contained in large tin sauce-dishes. It was found that the tea- 
kettle was excellent for sterilizing nutritive gelatin in test-tubes. For this pur- 
pose the tubes are suspended from a glass rod by means of cord or copper wire. 
Half a dozen tubes may thus be lowered into a large tea-kettle and effectually 
heated. The thoroughness of the process is well shown by the fact that the 
tubes thus prepared, nearly a month ago, are still perfectly clear and free from 
life. 
The only piece of apparatus that was not readily arranged was a culture 
oven which could be maintained at a constant temperature. This was dis- 
pensed with, but not without considerable disadvantage as well as inconve- — 
nience. However, it is not absolutely essential, except for special purposes, 
and the general work required in examinations of water progresses ee well 
without one, in this climate at least. 
The gelatin culture medium was prepared as follows: One hundred grammes 
of a French gelatin, that we found at a photographer’s shop,.was placed to soak 
overnight in 500 c.c. of water. Five hundred grammes of lean beef were 
chopped fine and also digested in 500 c.c. of w ater. On the following morn- 
ing the meat extract was strained through a thin woollen cloth, mixed with the 
softened gelatin, and the whole gently” warmed. Peptone is the proper ma- 
terial to Be added at this stage, but at the time we could not obtain it, so, in- 
stead of that, 20 grammes of Dr. P. B. Rose’s ‘ peptonized beef’ were used, 
and 5 grammes of salt. The peptonized beef is an excellent preparation of 
beef, which can be boiled without precipitation of albumen, and it was thought 
that it would serve the purpose very well. Experience has fully sustained 
that presumption. 
After carefully neutralizing the free acid with carbonate of soda, the beaten 
white of an egg was thoroughly mingled with the solution, which was then 
poured into a | Mason } jar and heated in boiling water over the kitchen fire. 
The addition of the white of an egg is not usually recommended, but it cer- 
tainly expedites the filtration. The boiling must be continued for fully an 
hour, so that the albumen coagulum becomes very firm. The liquid may 
then be strained through a linen handkerchief, and it comes through remark- 
ably clear. The next operation is to reheat the solution and filter it through 
paper in the apparatus already described. The filtrate must be perfectly clear 
and transparent. It is then poured into sterilized test-tubes, filling them to 
the depth of about an inch, and protected by plugs of cotton. The tubes are 
then heated in the tea-kettle of boiling water, as already described. The heat- 
ing should be continued one hour, and repeated twice, at intervals of twenty- 
four hours. The medium will thus be perfectly sterilized. The sterilized 
gelatin used by Dr. T. Leone is composed as follows :— 
Water, ; ; : | | 1OO:0'parts: 
Gelatin, : : , 2 , TO: Ones 
EPLOMe sn! : : : O: 5 more 
Extract of meat, : : ; Os 5h) ear 
Sodium phosphate, . ; OLS ae 
Sodium carbonate to faint alkaline reaction. 
The water to be tested was obtained from some ice that had been condemned 
by the Japanese examiners as unfit for use, and the importers wished to know 
more about it. The water was collected in a sterilized flask, and immediately 
upon arriving home half a cubic centimetre of the water was mixed. with the 
culture medium 3 in one of the tubes and poured upon two prepared glass plates, 
each about four inches square. To cause the gelatin to set quickly a finger- 
