June 6, 1913] 



SCIENCE 



873 



(editor of the Zeitschr. f. wissenschft. Inselc- 

 tenbiologie) has undertaken to issue a more 

 extensive work. It is significant of the in- 

 creasing specialization in entomology that this 

 new work is not the product of one author, 

 but of eleven. It is divided into three parts : 

 Volume I. is on the Anatomy, Embryology, 

 Morphology, and Metamorphosis, and is pre- 

 pared by Dr. C. Borner, Professor P. Dee- 

 gener, Dr. J. Gross, and Dr. O. Prochnow. 

 Volume II. will treat of the Habits, Distribu- 

 tion. Economic, and Experimental Entomol- 

 ogy, and will be written by Dr. Schroder, Dr. 

 K. Eckstein, Dr. O. Heineck. Dr. K. Hold- 

 haus, Dr. L. Eeh, and Dr. H. Riibsaamen. 

 Volume III. will consider Paleoentomology, 

 Phylogeny, and Systematics, and is to be pre- 

 pared by Dr. A. Handlirsch. The portions 

 now issued (three parts of Volume I.) are 

 almost wholly by Dr. Deegener. Chapter I. 

 is on the skin (including color, scales, skin- 

 glands, scent-glands, wax-glands, etc.) with an 

 appendix on the sound organs; Chapter II. 

 treats the nervous system (especially the 

 larger ganglia) ; Chapter III., the sense- 

 organs, largely histological. In this chapter 

 are various minor errors; the great family 

 Capsidse is not mentioned under Heteroptera 

 as being without ocelli, the Panorpatse are 

 stated to have three ocelli, although on a 

 previous page the genus Boreus is correctly 

 stated to be without ocelli, and the various 

 cases of ocelli in Coleoptera are unmentioned. 

 The various sense-organs of unknown purpose 

 (pseudocelli, abdominal organs of moths, post- 

 antennal organs) are considered, as well as 

 the supposed correlation or rather comple- 

 mental development between the eyes and the 

 antennae. Chapter IV. considers the alimen- 

 tary canal and its appendages (salivary 

 glands, malpighian glands, anal glands) and 

 is very complete, as Dr. Deegener is particu- 

 larly interested in this matter. Chapter V. 

 is on the respiratory organs, and is rather one- 

 sided, most attention being given to respira- 

 tion in aquatic insects and in parasites. 

 Chapter VI. treats of the circulation, blood, 

 heart, the specific heat of insects, fat-bodies, 

 light-organs (rather briefly) and cenocytes. 



Chapter VII. relates to the endoskeleton and 

 muscles. The muscular system of the imago 

 of Dystiscus (as given by Bauer) is taken as 

 typical, with but little comparison to other 

 insects or larvae. Only a brief summary is 

 given of the endoskeleton, and brief treatment 

 of muscular contraction, attachments of mus- 

 cles, and muscular power of insects. 



The most useful feature of the work is the 

 long bibliographies at the end of each chapter. 

 Although not by any means complete (Amer- 

 ican references often lacking) these lists fur- 

 nish references that are difficult to secure but 

 essential to any one studying these subjects. 

 In fact, so useful is this new '' Handbuch " 

 that we hope a group of our entomologists will 

 plan an American work on the same general 

 lines. Nathan Banks 



TBIALS AND TROPISMS 

 I 



Some years ago' I attempted an analysis of 

 the facts grouped under the familiar but ap- 

 parently confusing term " tropism theory." 

 In the light of my experience I found myself 

 seriously questioning the validity of a view 

 that had just been published by Jennings in 

 his well-known book, " The Behavior of the 

 Lower Organisms." The issue was essentially 

 this: whether tropisms are developed through 

 selection from overproduced movements by 

 means of the method of trial, or whether they 

 are primary responses in the same sense that 

 these overproduced movements are, and not, 

 therefore, products of a process of selection 

 as suggested. 



Jennings soon found opportunity to reply 

 to my objections as well as to those of other 

 critics, notably Loeb and Parker. His reply, 

 however, does not appear to have convinced 

 them, for they have both taken issue since 

 with his conception of the nature of tropic 

 reactions. And though, up to the present, I 

 have not thought it either necessary or de- 

 sirable to add my own misgivings to a rapidly 



' ' ' The Method of Trial and the Tropism Hy- 

 pothesis," Science, N. S., XXVI., pp. 313-23, 

 September 6, 1907. 



