Abstract
Employing the antigen titration outlined in the previous paper, the question arose to what extent the preparation of antigen may be varied without affecting the final results. The following antigens were accordingly prepared, titrated with salt solution and smallest amounts of the latter used which produced opalescent antigen-salt solution mixtures. The tests were carried out with positive and negative sera according to procedures I and II.
Antigen 1. This was prepared as described in a previous paper of these Proceedings. 1 Dried beef heart was freed from ether extractives and subsequently extracted in 95 per cent. alcohol for 9 days in the ice box and overnight at incubator temperature. Color approximated potassium bichromate color standard.
Antigen 2. After extracting the dried heart with ether in the usual manner, boiling alcohol was poured on the dried material, shaken and extraction continued for 1 day in the incubator. Color approximated potassium bichromate standard.
Antigen 3. Same as antigen 2, except that the alcohol extraction was carried out in the water bath at 37.5° C. for 2 days with frequent shaking. Same color index as above.
Antigen 4. Same as Antigen 1, to which was added a second alcoholic extract carried out for 2 days at incubator temperature having approximately the same color range.
Antigen 5. Ether extractives were removed in the usual manner and dried heart muscle extracted with alcohol for three hours in reflex condenser.
Antigen 6. Ether extraction carried out for 1 hour in reflex condenser, followed, after filtration and washing with fresh ether and drying, by alcohol extraction also by means of a reflex condenser for 1 hour.
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