542 



SCIENCE 



[N. S. Vol. XXXI. No. 797 



Lecture V., Temperature Eadiation, gives a 

 very brief resume (with a new notation) of 

 the laws ai temperature radiation. In the 

 generality of the statements, however, ac- 

 curacy is ofttimes overlooked. It is not true 

 that (p. 74) "Practically all bodies give the 

 same temperature radiation, i. e., follow the 

 temperature law (1)" (which states that the 

 total emissivity is proportional to the fourth 

 power of the absolute temperature). For most 

 substances investigated the exponent should 

 be greater than " 4," in some cases (see recent 

 investigation by Coblentz, Bureau of Stand- 

 ards Bulletin, Vol. 5, p. 339) as large as 6 or 

 even 7. Little attention is given to the effect 

 of selectivity (though slight mention is made 

 of it) in determining the high efficiencies of 

 some sources, such, for example, as the 

 osmium lamp. It is at least questionable 

 whether (p. 80) the melting point of osmium 

 is higher than that of tantalum merely be- 

 cause it can be operated at a higher efficiency. 

 Osmium undoubtedly is distinctly selective. 



On the whole, although the book is extremely 

 interesting to the technical reader and is 

 quite suggestive, there would appear to be a 

 lack of care in gathering together the facts, 

 and a somewhat too dogmatic style in pre- 

 senting those topics which are still more or 

 less in the domain of speculation. The color 

 pyrometer described on pp. 89-90 is appar- 

 ently a real instrument, but any attempt to 

 reproduce it would soon convince one that no 

 mixture of spectrum yellow and spectrum 

 blue would give a green that could be matched 

 in hue with spectrum green. Numerous small 

 errors, both typographical and factual, could 

 be cited, but would scarcely strengthen the 

 conclusion that an early revision of the book 

 would be most welcome. 



The reviewer desires, however, to express 

 his appreciation of the service which this 

 book has rendered in coordinating the closely 

 related phenomena of physics and physiology 

 in their relation to illumination, and in call- 

 ing attention to many vital questions of il- 

 lumination which are frequently given too 

 little attention in practise (such as those of 

 directed and diffused illumination, shadows, 



the effects of sources of high intrinsic bright- 

 ness in the field of view, etc.) . 



Edw. p. Hyde 

 Physical Laboratory, 

 National Electric Lamp Association, 

 Cleveland, Ohio 



Die Sdugetierontogenese in ihrer Bedeutung 



fiir die Phylogenie der Wirbeltiere. Von A. 



A. W. HuBRECHT. Jena, Gustav Pischer. 



1909. Pp. 247, 186 test figures. 



Most zoologists know that Professor Hu- 

 brecht has been an assiduous student of 

 mammalian embryology for many years. The 

 reviewer well remembers the beautiful prepa- 

 rations — probably of Tupaja — exhibited by the 

 author at the Oxford meeting of the British 

 Association in 1895. 



The appearance of a volume on the subject 

 from such experienced hands may be sup- 

 posed to be an occurrence of no little interest 

 to students and teachers in this province of 

 biology. Whether the volume that actually 

 comes to us fulfills expectations depends 

 largely on what the particular user may feel 

 in need of, and what his standpoint may be 

 with reference to the more general problems 

 involved. 



If one be chiefly desirous of a manual that 

 should set forth the main facts of mammalian 

 development positively ascertained up to the 

 present moment, along with such generaliza- 

 tions as a conservative zoologist might recog- 

 nize as truly illuminating and not objection- 

 ably forced, the book can not be very satis- 

 factory, so it would seem. 



If, on the other hand, one would wish to see 

 how strong a case a competent specialist can 

 make of a fundamental theory of his own, 

 then the work may be adjudged satisfactory. 

 What we have essentially is a case of special 

 pleading, as indeed the title permits if it does 

 not intend us to infer. Not mammalian on- 

 togeny, but such ontogeny in its significance 

 for vertebrate phylogeny, is the aim. 



This statement is not intended to give the 

 impression that the reader longing for facts 

 primarily will find nothing to his purpose. 

 Not only the text but the many figures present 

 very many facts. Such a summary, for ex- 



