68 



SCIENCE 



[N. S. Vol. XXXVI. No. 915 



There do not at present appear to be any 

 considerations, either of theory or fact, which 

 would limit the applicability of these laws to 

 the comparatively narrow field to which the 

 term photoelectric effect is usually restricted. 

 For instance, there is no apparent reason why 

 they should not be applicable to the ionization 

 produced by such radiations as the Eontgen 

 and 7 rays. Moreover the deduction makes no 

 essential use of the fact that the particles have 

 been supposed to be electrically charged; so 

 that similar laws may be expected to charac- 

 terize the reversible formation of gaseous 

 chemical products under the influence of 

 setherial radiations. 



There is one other point. Equations (1)- 

 (6) have been derived without making use of 

 the hypothesis that free radiant energy exists 

 in the form of " Licht-quanten," unless this 

 hypothesis implicitly underlies the assump- 

 tions: (A) that Planck's radiation formula is 

 true, (B) that, ceteris paribus, the number of 

 electrons emitted is proportional to the in- 

 tensity of monochromatic radiation. Planck^ 

 has recently shovsTi that the unitary view of 

 the structure of light is not necessary to ac- 

 count for {A) and it has not yet been shown 

 to be necessary to account for (5). It ap- 

 pears therefore that the confirmation of equa- 

 tions (3), (5) and (6) by experiment does not 

 necessarily involve the acceptance of the uni- 

 tary theory of light. 



O. W. ElCHARDSON 



Palmer Physical Laboratory, 

 Princeton, N. J. 



THE cape lobster 



In noticing the peculiar history of the ani- 

 mal from the Cape of Good Hope, designated 

 under this head, I wish both to correct an 

 error, and at the same time to direct attention 

 to a little known individuality among the 

 higher Crustacea. 



In a review of Dr. Caiman's volume, " The 

 Life of the Crustacea," ' this much abused 

 animal was thus referred to: 



•See Science, N. S., Vol. XXXV., No. 892, 

 February 2, 1912. 



^Ber. der. Deutseli. Physih. Ges., 1912. 



We thought that this Somewhat shadowy species 

 had never recovered from the aspersions cast upon 

 it by Professor Huxley. 



Dr. Caiman has kindly called my attention 

 to the fact that the species is really a very 

 substantial shadow, that its nebulous reputa- 

 tion disappeared some years ago, and that 

 Huxley's remarks were not whoUy justified in 

 1878, for the elder Milne Edwards had pub- 

 lished a good figure of the animal as early a3 

 1851. Indeed, as we shall see, his still earlier 

 description was based upon an actual specimen. 



In my first extended report upon the Amer- 

 ican lobster^ the little Cape species was thus 

 referred to: 



A third form, H. capensis, has been imperfectly 

 described from the Cape of Good Hope, but it is 

 doubtful if it belongs in this genus. 



Such doubt as then existed has since been 

 cleared up, and the species should have been 

 included in my recent work on " The Natural 

 History of the American Lobster." ' 



The facts regarding the literary history of 

 this neglected species are briefly as follows: 

 It was first figured and described by Herbst 

 under the name of " The Cape Crayfish," 

 Cancer (Astacus) capensis, in 1796,* and in 

 a way to puzzle all future students who placed 

 any confidence in his statements. Under the 

 head of " The Cape Crayfish " was this brief 

 description : " Museum Spengler. Astacus, 

 slender, with smooth thorax; claws (manus), 

 hairy, with crenate border; all the legs 

 chelate"; followed by this even more vague 

 and contradictory account: 



This beautiful crab (Krebs) occurs at the Cape 

 in mountain streams. It is similar indeed to our 

 common crayfish, but is more slender, and of equal 



'"The American Lobster: A Study of its Hab- 

 its and Development," Bulletin of U. S. Fish 

 Commission for 1895, p. 8. 



' Bulletin of the Bureau of Fisheries, Vol. 

 XXIX., Document No. 747, issued July 13, 1911. 



* Johann Friedrieh WUhelm Herbst, ' ' Versuch 

 einer Naturgeschiehte der Krabben u. Krebse, 

 nebst einer systematischen Beschreibung Arten. 

 B. 2, Krebse," Tab. XXVI., Fig. 1, and p. 49. 

 Berlin u. Stralsund, 1796. 



