600 
PHYSIOLOGY: A. R. MOORE 
cramped bending of the neck. The tentacles also show convulsions. 
At the same time a lively expansion of the chromatophores takes place 
in the entire head region and solely in this region. Only rarely may the 
display extend to the mantle. 
In sea water one-sixth saturated with camphor gum, the reaction of 
young squid is exactly the reverse of that in caffein. While the head and 
tentacles remain passive and their chromatophores closed, the muscular 
spasms and the play of color take place in the mantle. The fact that 
the camphor acts directly on the mantle (stellar) ganglia may be demon- 
strated in the following way. With the stroke of a sharp scalpel sever 
the head from the body of the squid. In a few seconds the results of 
mechanical stimulation have abated and both parts are at rest with the 
chromatophores closed. Now put the two parts of the animal, head 
and body, into the camphorated sea water. The mantellar region 
shows muscular convulsions and the brilliant play of chromatophores, 
while the head and tentacles remain quiescent unless stimulated 
directly. 
Juvenile squid immersed in atropin sulfate solution (1 : 2500) show 
abnormally rapid swimming movements, soon followed by failure of 
locomotion. The animals lie on the bottom of the dish and with the 
microscope one may see the spasmodic contractions of the tentacles and 
mantle. There is no play of the chromatophores. This fact distin- 
guishes atropin spasms from those due to strychnine, caffein and cam- 
phor. It may be that the failure of the radial muscles of the chromat- 
ophores to contract is due to the blocking of the impulses to these 
muscles. In such a case we would have an analogy in the action of 
atropin in paralyzing the terminations of the sympathetic in vertebrates. 
Crustaceans are far less favorable material for the study of the selec- 
tive action of drugs. This is undoubtedly in part due to a failure of the 
substance used to penetrate the tissues. The writer has shown that 
certain fresh water crustaceans are rendered more sensitive to light by 
treatment with solutions of strychnine, atropin and caffein.^ Striking 
results may also be obtained in marine forms with saturated solutions of 
camphor gum. Specimens of the hermit crab (Pagurus longicarpus) 
after a few minutes' immersion in the solution of camphor gum in sea 
water are seized with tremors at each attempt at locomotion. This is 
due to the fact that all the appendages are thrown into convulsive trem- 
bling movements resembling the symptoms of palsy in human beings. 
Similar effects may be observed in the marine shrimp (Crangon vul- 
garis). In this form the thoracic appendages first show tremors, then 
complete paralysis. The swimmer ets are next extended at right angles 
