The normal and abnormal response of amoeboid cells (amoebocytes of limulus) to stimulation.

Abstract

Various considerations suggest very strongly the conclusion that the formation of acid within the amoebocytes is the factor directly responsible for the production of pseudopods and amoeboid movement. It seemed that it might be possible to obtain direct evidence bearing on this problem by allowing substances differing in their chemical and osmotic properties to act on the amoebocytes after the latter have migrated out of the piece of amoebocyte tissue into the surrounding blood plasma of Limulus. However, numerous experiments of this character proved that the amoebocytes respond to stimulation of various kinds with the sending out of normal or abnormal pseudopods and the consecutive movement of the granduloplasm into the latter. The response of these cells does, therefore, not primarily depend upon the character of the external stimulus, but upon the constitution of the cell which is such that it needs to react invariably with certain changes which when taking place in a definite sequence in a cyclic manner lead to effective amoeboid movement. The amoeboid cell is, therefore, as specifically constituted as the muscle, nerve or gland cell which all react to stimulation of various kinds in their own specific manner.

However, the intensity of the reaction and the character of the movement vary according to the medium which acts on the cells. In general substances which tend to withdraw fluid from the cells and thus increase the viscosity of the protoplasm, call forth the production of thread and sharp tongue pseudopodia, and slow the movement of the exoplasm and granuloplasm, while substances which favor the taking up of fluid on the part of the cells cause the formation of more rounded pseudopods, of drops and balloons, and a more rapid movement of the granuloplasm, which under these conditions tends to fill the balloons more completely.