PHYSIOLOGY: A. G. MAYER 
597 
7 Shonkinite: ourose-shonkinose. (II)III. (5)6. 2(3). 3. Laccolith, road S. of Bulu 
Saraung. E. W. Morley. 
8 Shonkinite: ourose-shonkinose. III. (5)6. 2(3). 3. Stream, Malawa. E. W. Morley. 
9 Leucitophyre: ourose-ottajanose. III. '6. (2)3. 2(3). Stream, Batuku. E. W. Morley. 
10 Shonkinite: kamerunose-cascadose. 'III. (6)7.2.3(4). Laccolith E. of Malawa. E. 
W. Morley. 
11 Leucitophyre: . IV. '2. i. 1. \. 2(3). Stream, Malawa. E. W. Morley. 
12 Batukite, leucite-limburgite, brunose-belcherose. IV. 1(2). 2. 1. 2.(3). 1(2). Batuku. E. 
W. Morley. 
ON THE NON-EXISTENCE OF NERVOUS SHELL-SHOCK IN FISHES 
AND MARINE INVERTEBRATES 
By Alfred Goldsborough Mayer 
DEPARTMENT OF MARINE BIOLOGY. CARNEGIE INSTITUTION OF WASHINGTON 
Communicated August 30, 1917 
Experiments made at Tortugas, Florida, during the summer of 1917 
indicate that the nervous systems of fishes and invertebrates are re- 
markably resistant to the injurious effects of sudden explosive shocks 
transmitted through the water. 
Many experiments were made upon the Scyphomedusa Cassiopea 
xamachana. The medusae were paralyzed by removing their marginal 
sense organs, and then a ring-shaped strip of subumbrella tissue was set 
into pulsation by an induction shock; thus producing a single neuro- 
genic contraction which travels through the circuit-shaped strip of tissue 
at a uniform rate of speed, provided temperature, saHnity and other 
factors remain unchanged. It is thus possible accurately to ascertain 
not only the rate of nerve conduction but also the peculiar individual 
characteristics of the wave in each pulsating ring. 
These rings were placed in a light silken bag immersed about 10 feet 
below the surface of the sea; and then a half stick of dynamite was ex- 
ploded within 3 feet of them. This, however, produced no effect either 
upon their rates or the character of their pulsation waves, although 
fishes possessing swim-bladders were killed within 10 feet, and injured 
so that they turned ventral side uppermost within 20 feet of the exploding 
dynamite. 
When the pulsating rings were placed in glass jars or tin cans, partially 
filled with air, the containers were crushed or shattered by the explosion 
and much mechanical injury sustained by the medusa rings, which 
however, could at once be restored to normal pulsation by an induction 
shock, if their pulsations had ceased. It was also observed that the 
lacerated area regenerated at a normal rate. 
Prof. J. F. McClendon suggested that fishes with swim-bladders might 
