Abstract
The precipitation reaction presented in the preceding paper may be employed also as a microscopic procedure. Prepare hanging drop preparations in the usual manner by mixing a small drop of serum with the same amount of antigen. Read results after 1 and 3 hours incubation at 37.5° C. Those sera showing precipitation give the appearance of clumps of minute globules, while the negative sera appear homogeneous. This procedure, however, requires much experience and care in its manipulation.
The following micro-method is, in our experience, far simpler to execute and is recommended: Pipette 0.03 c.c. quantities of serum in narrow agglutination tubes and add 0.02 c.c. of antigen to each tube. Incubate in water bath and read as in the case of the regular quantities described in the preceding paper. Although the total quantity employed in this test is only about 1/10 of the original one, the precipitates can nevertheless be seen with the naked eye. We would, however, recommend this test only in cases where it is extremely difficult or impossible to obtain larger quantities of serum.
Get full access to this article
View all access options for this article.