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I see no evidence that either Mr. HAFFKINE or Professor SIMPSON undertook a series of post-mortem examinations by killing day by day animals fed at the same time in order to watch carefully the daily progress of the pathological events following the feeding.
Professor SIMPSON's experiments were not conducted in a laboratory designed or even adequately adapted for such important work. A large shed was obtained (an oil godown) and the animals were kept there. The post-mortem examinations were made in the same shed and near the doorway for the sake of light.
The microscope, table and necessary record books were at one end of the same shed.
Moreover there was a continual going to and fro in the shed of those engaged in carrying out the details of the experiments.
During the carrying out of those experiments one of the assistants a Chinese butcher employed to help in the post-mortem examinations-was attacked by plague. The circumstance is recorded in the report of Dr. HUNTER already referred to, page 12.
This case may be cited as evidence that the animal on which he was working at the time he wounded himself was in reality suffering from plague. This animal was a pig.
Dr. HUNTER does not state whether this particular pig had been fed or other- wise experimentally infected.
At the time of the accident I distinctly remember being told that the butcher was bitten by the pig. This might make a considerable difference in the deduct- ions to be drawn from this accident, as if the pig had been fed with plague material shortly before, a bite from it might infect with plague even although the animal were not suffering from a general plague infection.
In Dr. HUNTER's record of this case, however, the wound is stated to have occurred from an accidental scratching of the hand by a broken rib.
Again there has not been eliminated the possibility of the man's infection being from another source than this particular pig. He was daily employed in the shed where organs from human sources of plague had been used as food for animals.
But whatever may be the eventual outcome of the difference of opinion on the subject of plague infection in farmyard animals, for the purpose of discussing from other points of view the probability of infection in men being through the ingestion of infected food, I will assume for the sake of argument that some of the animals experimented on by Professor SIMPSON were in reality infected with plague.
While therefore it may be borne in mind that plague may be induced by the ingestion of infected food, it cannot be accepted that the experiments referred to above were instituted on lines offering the nearest approach in laboratory methods to conditions which obtain in nature.
That the prevalence of plague amongst rats and possibly sometimes pigs may be due to their foul habits of feeding in the East is possible, and that the preva- lence of the disease amongst rats must be a great source of danger to the populace amongst which such an epizootic is occurring is an accepted doctrine. But that the transferrence of the disease from these animals to man is due more to the eat- ing of the flesh of infected animals or of other food which has been contaminated by them, than to infection through another channel than the gastro-intestinal tract is by no means obvious.
*1 *#*#
The animals experimented on were fed with the raw material, with blood organs and tissues derived from previously infected animals. There is no recorded experiment in Professor SIMPSON's report on the feeding of pigs on the "pig- wash,' or on cooked food to which a slight amount of excretal matter from a plague case had been added, nor is there any record of a pig fed with the kind of material which it naturally finds in its free wanderings about a Chinese village, whether or not such material was purposely mixed with excretal matter from a known case of plague, human or otherwise.
*Pig-wash is the kitchen slops from dwellings and restaurants.