598 
PHYSIOLOGY: A. R. MOORE 
prove to be more sensitive to explosive shocks than those without swim- 
bladders, and experiments showed that a half stick of dynamite may be 
exploded within 3 feet of a small shark, which has no swim-bladder, 
without producing any apparent injury. This also applies to a lesser 
degree to such teleosts as lack swim-bladders. Dr. S. C. Ball kindly 
dissected some of the fishes with swim-bladders which had been killed 
by the explosions, and found that the swim-bladder had burst, and the 
tissues were crushed in around it, often breaking the vertebral column 
of the fish. Moreover, Prof. W. H. Longley, who has had much experi- 
ence in the use of dynamite, tells me that echinoderms, and Crustacea, 
if not mechanically torn apart, show no apparent ill effects but how- 
ever move away from the site of the explosion. 
It appears, then, that the nervous system of these lower forms is ex- 
traordinarily insensitive to shock due to explosion of dynamite, and that 
the injurious effects of the explosion if present are due to mechanical 
lacerations of tissues and especially the crushing inward of air-filled 
cavities. It seems possible, therefore, that the cavities of the middle 
ear and eustachean tubes may be a source of danger to men standing 
near exploding shells. 
It has been suggested that the sudden reduction in atmospheric 
pressure in the close proximity of an exploding shell might set free dis- 
solved gases in the blood and elsewhere, thus vacuolating the tissues 
and producing pressure and other effects upon the nerves; but our ex- 
periments with pulsating rings of Cassiopea seem to negative this hy- 
pothesis for no injurious effects other than those of simple asphyxia- 
tion were produced by sudden exhaustion of the air surrounding the 
animals; and recovery, when replaced in normal sea water, was almost 
immediate. 
These results are in accord with the conclusion of Grasset, Eder, 
Babinski et Froment, and others that war shock is predominantly a 
psychic phenomenon, and being hysteria it can be cured by hypnotic 
suggestion. 
CHEMICAL DIFFERENTIATION OF THE CENTRAL NERVOUS 
SYSTEM IN INVERTEBRATES 
By A. R. Moore 
RUTGERS COLLEGE. NEW BRUNSWICK. NEW JERSEY 
Communicated by J. Loeb, September 1. 1917 
The selective action of drugs for certain tissues forms the basis of 
the science of pharmacology. The action of such substances as strych- 
