Abstract
The resistance of the chick embryo to toxic substances is a subject which has been little explored in spite of the fact that the embryo is well adapted to a variety of bacteriological and physiological experiments. The developing egg consists of rapidly growing embryonic tissue in a perfect nutritional environment. It comes sealed in an ampule, the shell, which is readily opened for inoculation or other manipulation and easily sealed again for the period of rein-cubation.
The original purpose of the present study was to determine whether the fertile egg could be used as a medium for testing the inactivating effect of antiseptics on viruses. Such studies could be made only if the normal physiology of the embryo is not greatly disturbed by the injection of such agents.
Three tests were performed on different days with each substance. Embryonated eggs which had been incubated for 6 or 7 days were candled and the location of the embryo marked on the shell. This mark was kept uppermost until the inoculation was completed. A hole was drilled through the shell over the air sac by means of a 2 mm dental bur or a carborundum disc. The injection was made by means of a 2-inch, 20 gauge needle fitted to a tuberculin syringe. The needle was directed slightly upward and inserted 3 cm into the egg. The amount injected was 0.05 cc in each instance. This represents 1 part in 1000 of total egg weight, or the equivalent of 70 cc for a man weighing 70 kilos. The eggs were candled daily and the day of death noted. The results are shown in Table I.
The minimal lethal dose for man has not been determined for many of these substances.
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