February 1, 1918] 



SCIENCE 



121 



statements should be revised as in case of 

 the gas constant on p. 79, where the reader 

 would be puzzled if he did not understand 

 that a g:ram-molecule of gas is the amount 

 dealt with. Also we find quantity of heat 

 defined as " the total kinetic energy of the 

 molecule or ultimate particles of a body," 

 without explaining that this excludes what is 

 ordinarily called latent heat. In describing 

 the Nicols' prism the spar is said to be cut 

 along a " parallel plane " without indicating to 

 what the plane is parallel. In the statement 

 about vector potential the phrase " all lines of 

 magnetic induction " is used where the mean- 

 ing is, the total flux, or total number of 

 lines of induction. Also the interior of a 

 hollow enclosure at uniform temperature is 

 spoken of as at " black body temperature " in- 

 stead of as giving off the radiation character- 

 istic of a black body at that temperature. 



It is perhaps unfortunate that the author 

 has chosen Eankine as his soiu-ce for various 

 thermodjTiamic statements, for with all his 

 undoubted genius Rankine is not an easy 

 guide to follow, and the two statements of the 

 second law of thermodynamics which are 

 quoted from him are practically useless unless 

 interpreted by the fiiller discussion in the 

 original to which reference is given. We 

 should have expected a more modem state- 

 ment of so important a matter as the second 

 law, to supplement the statement by Clausius 

 which is given. 



But it is easy to be too critical ; the author 

 has successfully carried out his proposal and 

 has done an important service in bringing 

 together in this convenient form so large a 

 collection of the laws and principles of phys- 

 ical science, clearly and accurately stated, and 

 in the care with which the specific references 

 under each topic have been selected, making it 

 easy for the student to turn to sources where 

 the subject is more fully developed. 



The volume is well gotten up, with flexible 

 covers in handy form for reference, and has 

 a full index. A few misprints are noted, as 

 in formulas on pages 37 and 42, where the 

 figure 1 is used instead of the letter I. also in 

 the general equation for the flow of heat the 



coefficient of conductivity K is omitted, and 

 in the formula for the frequency of vibration 

 of a stretched cord the factor 21 does not 

 appear. A. L. Kimball 



THE PROCEEDINGS OF THE NATIONAL 

 ACADEMY OF SCIENCES 



The ninth number of Volume 3 of the 

 Proceedings of the National Academy of Sci- 

 ences contains the following articles: 



Heliotropic Animals as Photometers on the 

 Basis of the Validity of the Bunsen-Roscoe 

 Law for Heliotropic Reactions: Jacques Leob 

 and John H. Northrop, Eockefeller Institute 

 for Medical Research, New York City. New 

 quantitative experiments proving that the " in- 

 stinctive" motions of animals to light are 

 phenomena of automatic orientation and a 

 function of the light intensity, the function 

 being the Bunsen-Roscoe Law of photochem- 

 ical action. 



The Appearance of Reverse Mutations in 

 the Bar-Eyed Race of Drosophila under Ex- 

 perimental Control: H. G. ilay. Department 

 of Zoology, University of Illinois. Such a 

 phenomenon is not difficult of explanation on 

 the theory that it is produced by a chemical 

 change in the constitution of some substance. 



The Part Played hy Alcyonaria in the For- 

 m,ation of Some Pacific Coral Reefs: Lewis 

 R. Gary, Department of Biology, Princeton 

 University. On certain of the Pacific reefs 

 the alcyonaria are important coral-forming 

 agents ; their relative importance can be deter- 

 mined only after borings have been made 

 through some reefs to determine the history 

 of the reefs. 



Ohservations upon the Alkalinity of the 

 Surface Water of the Tropical Pacific: Al- 

 fred Goldsborough Mayer, Department of Ma- 

 rine Biology, Carnegie Institution of Wash- 

 in^on. 



The Effect of Temperature on Linkage in 

 the Second Chromosome of Drosophila: Har- 

 old H. Plough, Zoological Laboratory, Colum- 

 bia University. Both high and low tempera- 

 tures produce an increase in the percentage 

 of crossing over. The crossing over appears 

 to take place in the stage when the cliromo- 



