Laking of blood by drying

Abstract

Drying of blood may cause laking of the scarlet blood discs. 1 To obtain more information regarding the phenomenon, the experiments reported in this communication were undertaken.

The phenomenon may be produced in a number of ways. Perhaps the simplest is to prepare an ordinary wet blood mount and to observe it with a microscope. Another method is to make an ordinary blood smear and allow it to dry quickly in the air and then place it film side down on a microscope slide and after focusing it under a microscope, place a drop of serum, salt solution or other liquid on the slide, so that the edge of the drop forms contact with the edge of the slip and will spread under it.

Under these conditions laking occurs and may be readily observed in the individual discs.

In the case of a wet mount, the process is slow and various stages may be seen. If drying be rapid the individual discs may lose their hemoglobin with slight or no change in size. But if it be more gradual, they may be seen to swell before laking. This is also the case with shrunken or crenated discs.

In the case of dry mounts, the hemoglobin is almost instantaneously dissolved on contact with the liquid under the slip. If any change in the size of the discs occurs, it has not been observed.

At present the manner in which laking is thus produced is not known. Drying is, of course, accompanied by concentration of salts or other substances present in solution or suspension both within the discs and in the serum. Now it is known that hypertonic solutions of such substances if caused to act on the blood may produce laking.