220 



SCIENCE 



[N. S. Vol. XXXVII. No. 945 



It is also to be hoped that all persons who 

 approve of the proposition to reform the cal- 

 endar will write to the Swiss Federal Council 

 immediately, expressing their approval of and 

 giving their ideas on the subject. 



J. M. Clifford, Jr. 



SCIENTIFIC BOOKS 



Elementary Entomology. By E. Dwight 



Sanderson and C. F. Jackson. Ginn & Co. 



1912. Pp. vii + 3'r2. 



"During recent years there has been an 

 increasing demand for short courses in ele- 

 mentary entomology. For several years past 

 the authors have been endeavoring to present 

 such courses to their students, but have en- 

 countered the difficulty that no text-book was 

 available which met their needs. This book 

 is, therefore, the author's effort to furnish 

 such a text for beginners. . . ." 



In a brief introduction the authors point 

 out the important role insects play in the 

 transmission of disease, and emphasize their 

 importance as agricultural pests. Their ex- 

 planation of why insects are so numerous in 

 individuals and in species is not clear. " The 

 immense number of insects, both of species 

 and of individuals, is undoubtedly due to their 

 varied structure which enables them to live 

 under all possible conditions. . . . Thus the 

 insects possess such diversity of structure and 

 habit that they are able to live under all ex- 

 ternal conditions, and on account of their 

 immense numbers they have been able to adapt 

 themselves to a changing environment which 

 would have entirely obliterated classes or spe- 

 cies few in number." In other words, insects 

 are numerous because they are diverse in 

 structure and are diverse in structure because 

 they are numerous. 



The book is divided into three parts : I., 

 The Structure and Growth of Insects, 62 

 pages; II., The Classes of Insects, 208 pages; 

 III., Laboratory Exercises, 84 pages. 



In Part I. a brief chapter is devoted to the 

 near relatives of insects. The figure of the 

 spider illustrating the arachnida is from a 



photograph taken at such an angle that it does 

 not show the division of the body into cephalo- 

 thorax and abdomen mentioned in the text, 

 but does show the modified antennae (cheli- 

 cerse) which, according to the text, are not 

 possessed by Arachnida. The treatment of 

 the Myriapoda is inadequate even for an ele- 

 mentary text. No distinction is made be- 

 tween the Diplopods and Chilopods, and while 

 the figure shows a Diplopod with two pairs of 

 legs to each segment, the text says that " each 

 segment bears a pair of legs." The same 

 statement is repeated in the table on page 9. 



The twenty-four pages devoted to the anat- 

 omy of insects show the same evidence of 

 hasty and careless work. The original figure 

 of a typical maxilla of the grasshopper (Fig. 

 11) omits the cardo. We are told that the 

 mandibles are always essentially biting organs, 

 though many of the copied illustrations show 

 their piercing form. We would agree with 

 the authors that the mandibulate mouth-parts 

 of the different orders are " apparently homol- 

 ogous," but what reason is there for believing 

 that the types of suctorial mouth-parts are 

 " entirely dissimilar in structure and origin " ? 

 However, it is consistent with such a belief 

 that the illustrations of the mouth-parts of the 

 mosquito and horse-fly (18 and 20), "good 

 examples of the piercing type," should be 

 labeled without further discussion, according 

 to radically different interpretations, and that 

 Fig. 15 is referred to on page 18 as of dip- 

 terous mouth-parts, though it is correctly 

 labeled as hemipterous. 



We are told on page 24 that " the wings are 

 strengthened by numerous thickenings called 

 veins, whose number and position form the 

 basis of the classification of families, genera 

 and species." Then, important as the subject 

 would seem to be, a half paragraph, accom- 

 panied by an incorrectly labeled figure of the 

 wing of a house fly, is devoted to a summary 

 of the Comstock-Needham system, while in 

 the systematic portion thirteen dipterous 

 wings labeled according to this same system 

 are illustrated and the key to families uses 

 another system which is not even mentioned 

 — not to say explained — in the text. 



