Januaby 7, 1916] 



SCIENCE 



27 



THE TEACHING OF ELEMENTARY DYNAMICS 



To THE Editor of Science : Will you please 

 note that the following typographical errors 

 should be corrected in my article in Science 

 of December 24, page 901 : 



Pirst column, after (4) " Impulse = Mo- 

 mentum " should be raised two lines, and 

 "From (3)" should be brought down to the 

 line containing T = '28/V. 



After (5) "Work done = Kinetic energy" 

 should likewise be raised and "In (4) let" 

 lowered. 



Sixth line from bottom, for A=.M/F 

 read A=.F/M. 



Second column, third line, for Ffir/32.1740 

 read Wg,/32.17iO. 



Wm. Kent 



montclaie, n. j. 



SCIENTIFIC BOOKS 



Medical and Veterinary Entomology : A Text- 

 hook for use in Schools and Colleges, as well 

 as a HandhooJe for the use of Physicians, 

 Veterinarians and Public Health Officials. 

 By William B. Heems, Associate Professor 

 of Parasitology in the University of Cali- 

 fornia. The Macmillan Company, 1915. 

 Price $4.00. 



This is a time in the history of the world 

 when " long-felt wants " are rapidly being 

 jBlled. A year ago an up-to-date handbook of 

 medical entomology did not exist in printed 

 form, and now we have two excellent works on 

 this subject. The first to appear, " A Hand- 

 book of Medical Entomology," by Dr. W. A. 

 Riley and Dr. O. A. Johannsen, of Cornell 

 University, was reviewed in Science, October 

 15, 1915. The second, which has just ap- 

 peared, is a large, well-illustrated and com- 

 petent book of about four hundred pages, and 

 has been written by a man who has been in- 

 vestigating and teaching the general subject 

 for six years or more at Berkeley. Much of 

 the matter contained in the book was pre- 

 pared for the press some sis years ago, but 

 owing to the very many advances which are 

 constantly being made in the field covered by 

 the book it was withheld until this time, much 

 revised and added to, and now appears at a 



moment when it is very welcome. Although 

 the author states that his book is not intended 

 to be a comprehensive treatise, but is rather an 

 attempt to systematize the subject and to 

 assist in securing for it a place among the 

 applied biological sciences, it has greatly the 

 appearance of comprehensiveness. The whole 

 field is included in the treatment, and of 

 course for the pmposes of the volume the ticks 

 and mites are among the subjects treated. 

 There is also a chapter on venomous insects 

 and Arachnids. 



A thoroughly good compilation arranged in 

 a natural and systematic manner would have 

 been a most useful book for the teacher and 

 student as well as the practitioner, but in addi- 

 tion to being such a compilation this book in- 

 cludes a large amount of new material based 

 upon the researches of Professor Herms and 

 his assistants. Eor example, he details specific 

 experiments in the transmission of bacteria by 

 cockroaches and gives counts of the bacteria 

 of the different parts of the body of the croton 

 bug. His chapters on organization and cost of 

 mosquito control work and on organization and 

 control work against the house fly are espe- 

 cially strong from the very fact that they are 

 based upon extended experience and upon very 

 many experiments. Professor Herms himself 

 has been the adviser in nearly all of the organi- 

 zation and control work of this kind which has 

 been carried out on the Pacific coast, and what 

 he says in this direction is in the highest de- 

 gree authoritative. His chapter on the stable 

 fiy (Stomoxys calcitrans) is also strong, and 

 his conclusion to the effect that it is doubtful 

 that this species is the usual agent in spread- 

 ing polyomyelitis in nature is based upon a 

 careful series of experimental laboratory work 

 with this species and monkeys. The treat- 

 ment of the important group of fleas and ticks 

 is noticeably full, and his consideration of bee 

 stings, and especially of the morphology and 

 operation of the sting, is very welcome. 



In his generalizations concerning mosquito 

 life history, on page 91 and the following, he 

 does not sufficiently point out, it seems to the 

 writer, the enormous differences that exist in 

 the life histories of different species, which 



