232 Recent Literature. [ awh 
protection of wild life for its economic value to our trees, flowers and 
crops — and necessarily to man himself. 
This report should be read through by every one interested in wild bird 
life and every reader will we feel sure join with us in congratulating the 
National Association and its officers upon the completion of a most success- 
ful year’s work.— W. 8S. 
Lloyd-Jones on Feather Pigments.'— This investigation while car- 
ried on primarily in connection with the study of color-inheritance in 
Pigeons, has an important bearing upon the general subject of coloration 
in birds. The author finds that there are only two pigments in domestic 
Pigeons, a red-brown, which produces the red and yellow colors, and # 
black, which under different conditions produces black, dun, blue and 
silver. In typical “red” birds the pigment granules are about 0.3 m. in 
diameter; in ‘plum colored’ individuals they are 2.0 m. or more, while 
in yellows they are so minute that their granular structure cannot be 
determined. Blue as in all birds is a structural color but just what physical 
peculiarities of the feather produce it has not yet been determined. An 
interesting point in the author’s paper is that he finds that the black pig- 
ment may exist either in spheres or in rods so that genetically speaking 
we may have two different blacks which to the eye appear absolutely identi- 
eal. Mr. Lloyd-Jones is to be congratulated upon a piece of careful work 
in a field which offers opportunities for many important investigations.— 
W. S$. 
Grinnell on Distributional Control.?— Dr. Grinnell’s object in this 
interesting paper is to demonstrate that data secured through field observa- 
tion can be so employed as to bring results essentially similar to, and just 
as conclusive as, those secured through laboratory experimentation, in 
determining the factors which govern the delinitation of animal habitats. 
The cases of several species of bird and mammals are considered in detail 
and the possible effect of various environmental factors is carefully weighed. 
Dr. Grinnell finds that in the majority of cases which he has studied, 
temperature looms up as the most frequent delimiter of distribution, but 
he argues that this fact is in no way antagonistic to the claim that other 
factors such as humidity, food-supply and shelter also figure critically. 
The paper is suggestive and gives one a deeper insight into the complica- 
tions of a problem that we are perhaps too much inclined to regard as 
entirely solved.— W. S. 
Recent Publications of the U. 8S. Biological Survey.— Three bulle- 
tins have recently been issued by the U. 8. Biological Survey. One of 
1A Microscopical and Chemical Study of Feather Pigments. By Orren Lloyd-Jones. 
Jour. Exper. Zodl., Vol. 18, No. 3, April, 1915, pp. 453-495, pll. 1-7. 
2 Field Tests of Theories Concerning Distributional Control. By Joseph Grinnell. 
American Naturalist, LI, pp. 115-128, February, 1917. 
