324 Scientific Intelligence. 



The manner in which flies, mosquitoes, fleas, and other unwel- 

 come visitors to the household bring with them the germs of 

 some of our most dreaded diseases is clearly pointed out, and 

 simple directions are given for the extermination and exclusion 

 of these pests. Of the other insects which destroy the furnish- 

 ings of the home and the food and clothing of its members, the 

 book contains the necessary descriptions of the appearance and 

 habits of each species and of the means of preventing injury. 

 There are also included such insects as are annoying by their 

 bites or stings, those which are reputed to be poisonous, and 

 those which are parasitic upon the human body. The descrip- 

 tions are free from technical terms, and the numerous figures will 

 aid in the identification of the species. 



Of all branches of human knowledge, that pertaining to the 

 health and prosperity of the community is perhaps the most 

 important, and is in no small measure dependent upon a knowl- 

 edge of just such facts as are so clearly stated in this book. An 

 enlightened community may therefore reasonably expect of every 

 citizen some knowledge of the insects which endanger the home 

 and of the means by which they may be destroyed. w. r. c. 



2. The Germ-cell Cycle in Animals; by Robert W. 

 Hegner. Pp. x, 346, with 84 figures and an extended list of 

 references to literature. New York, 1914 (The Macmillan Com- 

 pany).— The author traces the history of the germ-cells from one 

 generation to the next in nearly all the species of animals in 

 which this history has been discovered. The account is based 

 largely on the author's own investigations in this comparatively 

 new field of study and shows how the germ-cells, which are 

 reserved for the perpetuation of the species, are very early in 

 embryonic life completely differentiated from those that are to 

 form the body itself. Although necessarily somewhat technical 

 in nature, no other treatise presents the subject so logically, 

 clearly, and exhaustively. The work is well illustrated, and the 

 facts presented will have an important influence on the modern 

 conceptions of the mechanism of inheritance. w. r. c. 



3. Dynamic Evolution: A Study of the Causes of Evolution 

 and Degeneracy ; by Casper L. Redfield. Pp. xi, 210. New 

 York and London, 1914 (G. P. Putnam's Sons). — The author 

 attempts to prove from an extensive study of the pedigree 

 records of trotting horses, and of cattle, dogs, and men, that the 

 characters transmitted to the offspring of any individual are 

 dependent in large measure on the reserve supply of energy 

 which the individual possesses at the time of reproduction. The 

 theory thus supports the formerly widely accepted Lamarckian 

 doctrine that the effects of use and disuse are heritable, but this 

 view is quite at variance with recent experience in experimental 

 breeding. w. r. c. 



4. Physikalische Chemie der Zelle und cler Gewebe ; von Prof. 

 Dr. Rudolf Hober. Privatdozent der Physiologie an der 

 Universitat Kiel. 4te Auflage. Pp. xvii, 808. Leipzig und 



