516 SCIENCE PROGRESS 



flea, and Ctenocephalus cants, the dog flea, is once again given the name Pulex 

 scrraticeps ! 



The volume is well illustrated and produced and should prove of value to 

 the various classes of readers to whom it is intended to appeal. In the present 

 work, however, it is perhaps unfortunate that the author has adhered so strictly to 

 the limitations implied by the title, as in this way certain groups of voracious 

 bloodsucking flies — not yet proven disease carriers — are excluded. 



H. F. C. 



Handbook of Medical Entomology. By W. A. Riley, Ph.D., and O. A. 

 JOHANNSEN, Ph.D. [Pp. ix + 348, with 174 illustrations.] (Ithaca, New 

 York: The Comstock Publishing Company, 1915. Price §2.) 



The contents of this volume are based upon a course of lectures delivered at 

 Cornell University during the last six years ; more specifically the work is an 

 elaboration of the senior author's Notes on the Relatio?i of Insects to Disease, 

 published in 1912. Its object is to provide a general survey of the subject, and 

 especially to acquaint medical and entomological students " with the discoveries 

 and theories which underlie some of the most important work in preventive 

 medicine." The subject-matter is arranged more from the medical than the 

 zoological point of view, and is primarily treated according to the ways in which 

 the various species of noxious arthropods affect man. Thus the contents may be 

 divided into four parts : arthropods which are directly poisonous (Chapter II.), 

 parasitic arthropods (Chapters III. and IV.), arthropods as disseminators of 

 disease (Chapters V.-XI.), and, finally, the more important morphological 

 characters of the various groups and species presented in a series of synoptic 

 tables (Chapter XII.). In each part, excepting the last, short historical accounts, 

 descriptions of the diseases, and eradicative or remedial measures are included, 

 and with those forms capable of disseminating pathogenic organisms the various 

 modes of transmission are discussed. 



Among the arthropods of a directly poisonous nature which receive attention 

 are spiders, scorpions, stinging insects, and the poisonous haired larva of certain 

 Lepidoptera, appropriately termed nettling insects ; blood-sucking forms also are 

 dealt with in this connection, but the majority receive more detailed treatment in 

 other parts of the work, in view of their more malignant functions as parasites or 

 disease carriers. Two types of parasitic arthropods are distinguished : the true 

 parasites, e.g. mites, ticks, lice, fleas, etc., and the accidental or facultative 

 parasites, which normally feed on decaying substances, but which, when acci- 

 dentally introduced into the system, may exist there for a varying period. Of the 

 latter certain kinds of fly larva; are pre-eminent, and those most frequently 

 encountered are discussed and their main structural and differentiating characters 

 shown in a useful key. The later and more important phases of the subject, 

 arthropods as disseminators or transmitters of disease-producing organisms, are 

 next inquired into and necessarily occupy considerable space. The various groups 

 concerned in this capacity are here classed and discussed with special reference to 

 the manner in which the transmission of the parasites is effected — the simple 

 carriers, the direct inoculators, and the essential hosts of disease germs. As 

 typifying those forms acting in the manner first mentioned, a well-developed 

 summary of the case against the house-fly is given, and the second or mechanical 

 method of transmission by blood-sucking arthropods is illustrated by a few 

 examples in which experimental proof has been obtained, and by an interesting 

 retrospective account of the role of fleas in the transmission of plague. Those 



