Chemotropism of Leucocytes in Relation to Their Rate of Locomotion. ∗

Abstract

A method was described 1 , 2 for measuring the chemotropic reaction of polymorphonuclear leucocytes in vitro. Leucocytes were observed with the microscope and their paths recorded as they approached bacteria or other sources of attraction. In measuring the reaction to these attracting bodies only the direction of the path was taken into account, not the rate of locomotion. It seemed possible, however, that leucocytes might respond to such attraction not only by moving toward its source but by traveling at increased speed. In this case it would be desirable to take account both of direction and of velocity of approach in measuring the chemotropic reaction.

The point at issue has been touched on by previous observers, 3 , 4 , 5 who, however, did not make actual measurement to compare the rate of locomotion of leucocytes approaching a source of attraction with that of leucocytes moving at random. We have made such a comparison by means of a simple method which has been described by one of us. 6

A minute clump of bacteria or of other particles is placed on a glass slide, where, after drying, it appears as a flat oval or circular body from 50 to 150 microns in diameter. A drop of blood, obtained by puncturing the finger, is placed on a coverslip, lowered on the bacterial mass and allowed to spread between slide and coverslip. The preparation is sealed with petrolatum and examined with the high power of the microscope in a warm box at 37°C.