OBSERVATIONS ON THE ERYTHROPHORES OF SCORPÆNA USTULATA

¹ From the Naples Zoölogical Station and the Department of Physiology, University of Tennessee, Memphis

1. Evidence is presented to show that the erythrophores of Scorpæna will respond to nervous stimulation.

2. Isolated scale erythrophores of Scorpæna will show rhythmical pulsations in N/10 NaCl after treatment with N/10 BaCl₂.

3. Isolated scale erythrophores of Scorpæna will show the following responses when immersed in the following drugs:

a. Nicotine in weak solutions (1/100,000-1/10,000) produces a primary expansion followed by contraction. Moderately strong solutions (1/10,000-1/2,000) produce a slight expansion followed by contraction. Strong solutions (1/2,000-1/100) produce a permanent expansion.

b. Physostigmine (0.0065-0.013 per cent) produces a "ringed" expansion.

c. Pilocarpine (0.016-0.04 per cent) produces a "ringed" expansion.

d. Atropine (0.025-0.0065 per cent) produces a "ringed" expansion. After atropine, however, the usual lasting contraction produced by N/10 KCl persists only a minute or so and is replaced by a permanent expansion. There is no change in the contracting effect of adrenaline after atropine.

e. Cocaine (0.1-0.01 per cent) produces a contraction.

f. Alcohol in strong solutions (10-5 per cent) produces first an expansion then a contraction and finally a "ringed" expansion. Weak solutions (1 per cent) produce a persistent contraction.

g. Acetyl-choline (0.1-0.01 per cent) had no effect.

4. No relation was found between the effect of drugs upon isolated scale erythrophores and their effects upon the color of the fish after injection into the abdominal cavity.

5. Hypophysis extracts of the tuna and Trigla produce a pronounced and lasting paling (erythrophore contraction) when injected into the abdominal cavity of Scorpæna ustulata.