View report page

16
it. On this point the opinions of various observers differ: while, for instance,
Kister and Kottgen, of Hamburg, to a certain extent confirm Danysz's statement,
others, like Krause, failed to confirm it.
1. Experiments in the Laboratory.—There is no difficulty in showing
the high virulence of the Danysz bacillus for rats, mice, and guinea pigs, if
inoculated subcutaneously or intraperitoneally, but it is different when the
material is administered by ingestion. While it is a fact that virulent culture
injected subcutaneously in a five division dose into each of 24 mice caused
death of all the animals in between 20 and 48 hours, when administered to
other mice by ingestion in large doses it caused death of these animals in
three, five, and eight days respectively. But the results were different with
rats, for in these the feeding experiments with culture produced death in only
33 per cent, between 8 and 14 days. There appeared, however, to be a
chance of causing the death of a larger percentage of rats by feeding these on
rodents dead of the disease after subcutaneous injection. Rats were fed on
mice which had died 48 hours after being subcutaneously injected with
virulent culture. None of these rats became ill or died. A number of rats
were fed on guinea pigs which had died after inoculation with virulent
culture, and here the percentage of dead rats was certainly increased. Of six
rats fed with the material from the guinea pigs (subcutaneous fluid, peritoneal
fluid, and spleen), four died from the disease in 11, 12, 11 and 18 days
respectively, and of three rats fed with one whole guinea pig, two died from
the disease in 7 and 11 days respectively. So much for the laboratory
experiments.
2. Experiments in the Warehouse.—The accompanying Table gives the
results of experiments of feeding on a large scale carried out in a Dock Warehouse
in the Port of London, instituted by Dr. W. Collingridge, the late
Medical Officer of Health, and continued by your present Medical Officer of
Health. It ought to be stated in explanation of this Table that the 60 tubes
of Danysz rat virus used between April 26th and May 31st were culture
tubes (on agar), which had been directly obtained from the Pasteur Institute
of Paris, and that the guinea pigs, mice, and rat used for the feeding experiments
from June 14th to July 17th had all been inoculated subcutaneously
in the laboratory with virulent culture of the Danysz bacillus, and
immediately after death from the typical disease were laid on the floors of the
warehouse. We would also draw attention to the fact that one rat which had
died after subcutaneous injection of the typical disease was offered to the rats
in the warehouse, but was not touched by them, whereas all the mice and the
majority of the guinea pigs were readily eaten by the rats of the warehouse.
The Table shows that, unlike the laboratory experiments, those carried out
in the warehouse were wholly negative, and therefore the expectation of a
wholesale destruction of rats by Danysz rat bacillus as a preventive measure
against Plague cannot be considered from the results of the experiments to be
of a promising nature.
This virus has been tried in various localities recently, and the results
practically correspond with those obtained by your Medical Officer and
Dr. Klein.