Arthus' reaction

No one likes it when their sandcastle is knocked over, but his reaction is a bit, err, extreme.

While this reaction lasted he laughed away the evidence, and honestly believed he was exaggerating trifles.

Ordinarily the diazo appears a little earlier than the Widal reaction—about the fourth or fifth day—but it may be delayed.

For Lettice—the tender woman of his first acquaintance—had obviously experienced a moment of reaction.

When applied to the diagnosis of typhoid fever, the phenomenon is known as the Widal reaction.

As yet, it is the only agglutination reaction which has any practical value for the practitioner.