ZOOLOGY: A. W. L. BRAY 59 
of the melanophores after the eyes were removed, both in normal and 
1 excited' animals, suggests that there is an adaptive significance to be at- 
tached to the reactions of the melanophores, and that these reactions are 
mediated by the nervous system through the eyes. 
Excised portions of the skin of Amiurus with melanophores expanded, were 
immersed in solutions of adrenalin of various strengths, others in tap water 
and still others in physiological salt solution, and the rates of contraction 
of the melanophores observed under the microscope. 
Strength of adrenalin solution Average time for maximum contraction 
1 : 5000 Almost immediately 
1 : 10,000 4 to 6 minutes 
1 : 100,000 6 to 8 minutes 
1 : 1,000,000 16 to 40 minutes 
1 : 2,000,000 120 minutes 
1 : 5,000,000 Partial contraction in 3 hours 
If an excised portion of the skin with melanophores contracted is placed in 
ether water, the melanophores expand slowly, whilst the controls, in physio- 
logical salt solution or in tap water, show no change. 
Intra-muscular injections of adrenalin were made, and others of physio- 
logical salt solution as controls. The results on the melanophores were in 
every way comparable to those found for the excised portions of the skin; 
that is, the melanophores contracted after injection of adrenalin at rates 
varying with the strength of the injection. The minimum dilution found 
effective was 1 : 5,000,000. An injection of 1 : 10,000,000 caused local con- 
traction of the melanpphores in the area around the point where the injection 
was made, but not in other parts of the skin. 
The effect of adrenalin disappears after a time varying with the strength 
of the injection and ranging from one to several hours. 
If a fish, which has been injected with 1: 1,000,000 part of adrenalin, is 
etherized when it has reached a condition of maximum contraction of the 
melanophores, there is a perceptible darkening, due to partial expansion of the 
melanophores. On coming out of the ether the fish returns to the light con- 
dition, that is, its melanophores contract. If the fish is subsequently kept 
in the dark the melanophores gradually expand. 
Some fish were removed for a time from the water and two pieces of filter 
p t aper, one moistened with physiological salt solution and one with a 1 : 100,000 
solution of adrenalin were placed on the skin. After fifteen minutes, both were 
removed. The area of the skin covered by the filter paper moistened with salt 
solution had become lighter, but darkened rapidly on removal of the paper. 
The portion covered by the paper moistened with adrenalin solution was 
quite light, and remained so for about three hours. The influence of the 
adrenalin spread only slightly to adjacent parts, but a light band appeared in 
some cases where a little of the solution had run down from the paper. 
