January 13, 19 16] 



NATURE 



533 



. peroxydase solution, and the analysis of diabetic 

 urine receive impartial attention. There is, How- 

 ever, an advantage in this plan, for the worker 

 proceeds from the simpler "organic " preparations, 

 in the course of which he acqliires the necessarv 

 technique, to the more difficult biochemical 

 methods. Owing, no doubt, to the necessity for 

 compression, some of the directions given for pre- 

 parations appear to be scarcely explicit enough for 

 a beginner, unless supplemented by verbal in- 

 struction — perhaps not a very serious fault. 



Turning to the more purely biochemical part of 

 the work, we find that a large number of prepara- 

 tions are described, and a very complete series 

 of illustrative experiments given in connection 

 with the more important branches of biochemical 

 work. Too little stress is, perhaps, laid on the 

 importance of the various factors by which bio- 

 chemical processes are affected. Thus, the deter- 

 mination of acidity — whether by electrical methods 

 or by the use of indicators — is not described, and, 

 in the section on fermentation, the reference to 

 the sensitiveness of enzymes to salts, acids, and 

 alkalis scarcely does justice to the importance of 

 the subject. 



Throughout the book the analytical relations of 

 the substances mentioned and the processes of 

 analysis employed in biochemical work are ex- 

 tremely well and fully described, the author's great 

 experience in this branch of the wOrk enabling 

 him to speak with special authority. Particularly 

 is this the case with the analysis of urine — -both 

 normal and pathological — the micro-methods of 

 Folin being included, the analysis of tissues, the 

 examination of the gases of the blood, and the 

 measurement of the activity of enzymes. 



As will be seen from the foregoing, the author 

 has brought together an extremely valuable col- 

 lection of information concerning substances, 

 processes and methods of biochemical interest, 

 and all students and workers owe him a debt of 

 gratitude for the industry and patience which he 

 has displayed in the accomplishment of this task. 



A. H.^RDEN. 



TIXEID MOTHS OF CENTRAL AMERICA. 

 Biologia Centr all- Americana. Insecta. Lepidop- 



tera-Heterocera. Vol. iv. By the Rt. Hon. 



Lord Walsingham. Pp. xii-t-482, plates x. 



(London : Dulau and Co,, Ltd., 1909-1915.) 



AS already stated in Nature (December 23, 

 1915, p. 448), the publication in 1915 of the 

 volume under review and of Dr. Godman's "In- 

 troductory \'olume " marks th^ completion of the 

 great series of works forming the Biologia Cefir 

 trnli-Americana. Lord Walsingham*^ contribution 

 NO. 24ill, VOL. q5l 



deals with the micr^-moths of the groups Tineina, 

 Ptercrphorina, and Orneodina, and includes a 

 supplement to Pyralidina and Hepialina. As he 

 explains in his introduction, the task has been 

 accomplished, not by himself alone, but by the com- 

 bined efforts of three specialists, the other two 

 being Mr. J. Hartley Durrant, and Mr. .\ugust 

 Busck of the United States Department of -Vgri- 



I culture. Lord Walsingham had already com- 

 menced to study the material so long ago as 1895, 

 but several causes have delayed the appearance of 

 the volume, notably the decision to extend it far 

 beyond its original scope as a faunistic treatise, 

 " and to give it special value for the future guid- 

 ance of all students of the Microlepidoptera." It 

 soon became apparent that previously adopted 

 lines of classification were inadequate for dealing 

 with so little known a fauna. Therefore a correla- 

 tion of the various systems and a revision of the 

 limits of existing family-divisions wei*e under- 

 taken — a Study which has produced interesting 

 results. 



Earlier writers relied to a large extent on 

 secondary sexual character's, not only for specific, 

 but also for generic, distinctions. These have 

 been discai^ded, for generic purposes at least, in 

 favour of characters found ih both sexes, this 

 b'eing probably the first time that such a principle 

 has been applied to the classification of Tineina 

 as a whole. The reason for this change, which 

 has involved the suppression of very many 

 genera, is that when the structural modifications 

 hitherto used "are carefully examined in relation 

 to the vast number of forms in a great continental 

 fauna, they are found to blend one into another 

 by such infinitesimal gradations as to impede 

 rather than to assist a conscientious worker." 

 For example, the genus Felderia was founded 

 on the strongly bipectinate antenna? of the male, 

 a character found to be modified by such count- 

 less and minute gradations as to be quite untrust- 

 worthy for purposes of generic differentiation. 

 Again, the family Acrolophidae, after being ex- 

 haustively examined, must be regarded as con- 

 sisting practically of one large genus, in which, 

 however, the species are separable by secondary 

 sexual differences. \'arying degrees of structural 

 divergence are often concomitant with most con- 

 fusing similarity of general appearance, so much 

 so that, in the case of the genitalia, the differences 

 may almost convey the impression of having been 

 purposely evolved to prevent interbreeding of 



I forms among which confusion might otherwise 



I occur. 



On the last page of the introduction is a census 

 of the forms enumerated : 27 families, two de- 

 scribed as new; 225 genera, 54 described as new; 



