Page:Blood examination.djvu/17

Rh night workers, and vice versa in filaria diurna.

It has seemed best to us to refer seriatim to various tropical diseases where blood examination is of known value, rather than make several sub-divisions according to changes in the appearance and number of the corpuscles, the parasites in the blood, agglutinative reactions, etc. etc.; for by this method there would be much overlapping, since most diseases show more than one change in the blood, and, consequently, would have to appear in more than one sub-division. Also, we do not propose to refer to all the changes seen, but rather to confine our attention to those which are of practical value.

It is only fitting that malaria should be referred to first: on account of its almost world-wide prevalence, its baneful effects upon mankind, the extremely varied forms of its onset and its characteristic blood appearances.

In few diseases does the examination of the blood afford us so comparatively easy a diagnosis, and in no other does it place us in so commanding a position as regards satisfactory treatment.

If the case is one of malaria we should be able to find the parasites, and not only so,