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A. Apex of Fibre. B. Root. C. Fibre showing central canal or medulla. |
COW’S HAIR
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A and B. Fibres showing central canal or medulla. C. Apex of Fibre. |
By kind permission of Messrs. Scott Greenwood & Co.
He prepared a 20 per cent. aqueous extract from the flesh of seven different species of animals, and injected small proportions of these beneath the skin of rabbits at intervals of three days. After a month the animals were killed, and the serum of the blood separated in a centrifugal machine.
In each case the specific sera were added to the clear filtered aqueous extracts of the flesh of the respective animals, and the tubes examined after the lapse of a specified time.
It was found that the sera only gave a turbidity or precipitate with the corresponding extracts. Thus the serum from the rabbit which had been treated with an extract of horseflesh only gave a reaction with preparations of horseflesh, and not with those of venison, beef, mutton or pork. In like manner, the serum from a rabbit that had been treated with an extract of rabbit’s flesh, only reacted with extracts of rabbit’s flesh, and not with those prepared from the flesh of cats, horses, or other animals, and so on.
In the case of mixtures the specific sera only reacted with extracts of the flesh of the two animals in question. Thus a rabbit treated with an extract from a mixture of the flesh of a hare, cow, deer, and pig, yielded a serum giving a precipitate with the extracts of the flesh of each of those animals, but not with that from any other animal.
It was not long before the possibility of using the method to distinguish between the blood of different kinds of animals suggested itself, and it was shown by Dr. de Nobel in 1902, that by treating a mouse or rabbit with any fluid, such as blood serum or saliva from a human body, it eventually produced a serum that would give a precipitate with human blood, but not with the blood of different species of animals.