RT Journal
T1 THe elementary nervous system.
JF Journal of the American Medical Association
JO Journal of the American Medical Association
YR 1919
FD August 30
VO 73
IS 9
SP 712
OP 712
DO 10.1001/jama.1919.02610350060030
UL http://dx.doi.org/10.1001/jama.1919.02610350060030
AB This volume, the second of a series of monographs on experimental biology by American investigators, includes an "extended discussion of only the simplest examples of the elementary nervous system" as Parker himself states in the opening sentence of the last chapter. The author shows that contractile tissue (as effectors in the form of muscle cells) appears before any form of nervous tissue. Subsequently, there is added a receptor or modified epithelial cell which influences the effector more quickly because it is more sensitive to the external stimuli (chiefly physical) which originally acted on the effector organ directly. It is a "trigger, so to speak, to discharge the underlying muscle, and judging from the quickness with which this discharge is accomplished as compared with that with which the independent effectors discharge, the efficiency of the new system is beyond doubt." To this receptor-effector system is added later on a third type