Literary Notices. 435 



be the case with the Cephalopod Elcdone moschata. He demonstrates 

 this admirably by tables and curves. Whereas the action currents of the 

 frog's retina, for he was careful himself to repeat the experiments of Him- 

 STEDT and Nagel, are the greatest for spectral light of about 590 nn 

 wave-length (yellow), those of the cephalopod's retina are greatest 

 around the wave-length 500 fxfx (blue-green). For considerably weaker 

 intensities of light the frog's retina gave the strongest currents for the 

 wave-length 560 nfx (yellow-green); that is, when the retina was more 

 less adapted to darkness the position of maximum currents shifted from 

 the yellow toward the yellow-green. This is in precise agreement 

 with HiMSTEDT and Nagel. 



For both animals the author used a dispersion spectrum from the 

 Nernst lamp ; and he bases his conclusions on experiments with 13 

 specimens of E. moschata. In view of the extreme similarity of the 

 results from the several individuals, this number seems quite sufficieixt 

 to establish the author's point. The author used this species alone, 

 because it was the only one which could be easily obtained and of 

 which the eye on being removed retains vitality enough to make ex- 

 perimentation possible. It is interesting to note that the action cur- 

 rent both attains its maximum and subsides very rapidly. Dr. Piper 

 does not confirm the results of Beck as regards the direction of the 

 action current. 



The paper is written with exemplary clearness and conciseness, 

 and cannot fail to convince the careful reader ; and this the more in 

 view of the rare and delightful modesty with which the author claims 

 to have established his interesting and important point. 



E. B. H. 



Keeble, Frederick, and Gamble, F. W. The Color-Physiology of Higher 

 Crustacea. Phtl. Trans. Roy. Soc. London, Ser. B, Vol. 196, pp. 295-388, 

 1904. 



Notwithstanding the fact that color patterns and color changes 

 have always interested naturalists greatly, and that much has been 

 written concerning "protective" coloration and "color mimicry," it is 

 only recently that color phenomena in animals have been subjected to 

 any very close and accurate scientific investigation, looking toward an 

 explanation of their origin. The work of Steinach, Rabl and Chun 

 on mollusks, and of Keeble and Gamble on Crustacea not only clears 

 up many points that were uncertain before, but will also doubtless stim- 

 ulate to further investigation in a field of inquiry that promises to be 

 most fruitful. 



The present monograph by Keeble and Gamble is one which de- 



