130 
ZOOLOGY: A. S. GILSON, JR. 
Proc. N. a. S. 
"expressions of protoplasmic responses to definite stimulating agents." 
The effect of adrenalin is the expression of the action of such an agent 
from the blood. Ether inhibits the activities of the melanophores arrest- 
ing them in whatever condition they may happen to be. 
Arey, L. B., 1916. The movements in the visual cells and retinal pigment of the 
lower vertebrates. /. Comp. Neurol., 26 (121-190). 
Gilson, A. S., 1922. The diverse effects of adrenalin upon the migration of the scale 
pigment and the retinal pigment in the fish, Fundulus heteroclitus, Linn. Proc. Nat. 
Acad. Sci., 8 (130-133). 
Spaeth, R. A., 1916. Evidence proving the melanophore to be a disguised type of 
smooth muscle cell. /. Exp. Zodl., 20 (193-215). 
THE DIVERSE EFFECTS OF ADRENALIN UPON THE MIGRA- 
TION OF THE SCALE PIGMENT AND THE RETINAL PIGMENT 
IN THE FISH, FUNDULUS HETEROCLITUS, LINN 
By a. S. Gilson, Jr. 
ZooLOGicAi. Laboratory, Harvard University 
Communicated April 25, 1922 
Bigney ('19), working w^ith the frog, found that the injection into the 
blood stream of this animal of small quantities of adrenalin caused a 
proximal migration (1) of the granules in the dermal melanophores of the 
skin and a distal migration of the granules in the melanophores of the retina. 
The present investigation was undertaken to determine if similar effects 
were to be found in fishes. 
For these experiments, the animal used was the common kilifish, Fundu- 
lus heteroclitus Linn. This fish shows a marked response, both in the 
scale (dermal) and the retinal melanophores to light and to darkness. 
When it is placed in the light over a white background, it shows a proxi- 
mal migration of the scale melanophore granules and a distal migration of 
the retinal melanophore granules. In the dark, these conditions are re- 
versed, the scale melanophores showing a distal and the retinal melano- 
phores a proximal migration. 
The method adopted for stating the effects of the adrenalin upon the 
retinal pigment was that of expressing the width of the retinal pigment ex- 
tension, as measured along processes showing maximal extension in the 
region measured, as a fraction of the total distance from the outer boundary 
of the pigmented epithelium to the external limiting membrane, this dis- 
tance being taken as 100. For purposes of brevity in this paper, the 
terms light fish and dark fish will be used to indicate fish which have been 
kept in the light and fish which have been kept in the dark, respectively. 
In the typical light fish, the pigment shows an average extension of 83 
units on this scale. Such light retinas show, in almost all cases, a secondary 
