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64
The symptoms of ptomaine poisoning are well-known,
viz.:—giddiness and drowsiness, vomiting and diarrhoea
(with or without pain), and subsequent collapse, to be followed
by death or a prolonged convalescence.
Unfortunately, there is no satisfactory chemical or bacteriological
test for these ptomaines, enzymes, or tox-albumens—the
only trustworthy one being the physiological
test, i.e., feeding animals (guinea pigs, rabbits, etc.) with
the suspected foods, and noting the effect on them.
Collapsed tins or cans must not be confounded with
"blown" ones—the former are due to pressure, and their
contents are wholesome and fit for food.
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Diseased Food in Tins or Cans, etc.
When diseased food is used for tinning or canning, it is
difficult to detect it after it has been put into the tins or
cans. To take an instance. A bullock with tuberculous
lungs might be killed, prepared and tinned (or canned) after
the diseased lungs had been carefullv removed. In this
case, no germs of tuberculosis might be found in the carcase
(apart from the lungs), though such carcase would be,
none the less, unwholesome and quite unfit for food. To
take another instance. Suppose a small piece of tuberculous
meat were mixed up with sound meat before tinning, or
canning, repeated examination of sample tins or cans might
fail to discover the germs of tuberculosis unless the particular
samples examined happened to contain part of the diseased
portion of meat.
From these instances it will be seen that bacteriological
examinations are not of much value in the examination of
the contents of tinned, or canned, and preserved foods from
the point of view of discovering actual germs of disease.
All such a bacteriological examination can hope to discover
is whether or not the food is sterile, i.e., whether the process
of tinning or canning has been efficient, and whether
the food was free from putrefactive germs when first tinned
or canned. What is wanted is a strict examination of all
foods previous to tinning, or canning, with strict hygienic
conditions under which such processes are carried on.