44 



SCIENCE 



[N. S. Vol. XLVII. No. 1202 



physiograpliic contribution of so great pos- 

 sible interpretative value as " Block Moun- 

 tains in New Zealand" be rendered almost 

 useless to the student of earth liistory by tbe 

 deliberate omission of all reference to geo- 

 logic dates? Surely tbe incidental mention 

 of tbe geologic age of tbe weak over-mass de- 

 scribed by Cotton, and of any other events 

 whose geologic dating may have been known, 

 would not have impaired tbe geographic value 

 of the paper. 



By all means let us eliminate unnecessary 

 and irrelevant geologic detail from geographic 

 or physiographic descriptions, but let us not 

 go to the extreme of rendering our geo- 

 morphologic studies valueless for their impor- 

 tant interpretative functions. 



John L. Rich 

 TJniversity op Illinois 



removing insects from greenhouse 



plants without spraying and 



without injury to the 



PLANTS 



When one is running experiments in the 

 greenhouse and the plants become infested 

 with insects, the disposal of the pests becomes 

 an important question. This question be- 

 comes all the more important if the nature 

 of the investigation will not permit the plants 

 to be sprayed. The writers were recently 

 faced with such a problem and solved it by 

 using an apparatus working on the principle 

 of a vacuum cleaner. 



A flask was fitted with connections similar 

 to those of a wash bottle, the mouthpiece be- 

 ing connected with a suction pump by a piece 

 of tubing sufSciently long to allow the flask 

 to be moved to any point desired. The nozzle 

 was extended to a point parallel with the bot- 

 tom of the flask and the opening made suffi- 

 ciently small to just allow the desired insects 

 to pass readily. By putting a small amount 

 of oil in the flask, for an insecticide, closing 

 the connections and turning on the pump, the 

 apparatus was ready for use. Small plants 

 that were thickly covered with aphids and red 

 spiders were quickly cleaned. Ants and 

 other insects were also readily taken up. It 

 is possible that this apparatus may be modi- 



fied to meet many requirements by simply 

 changing the size and shape of the nozzle, and 

 by using various kinds of motors and pumps. 

 Paul Emerson, 

 J. B. S. Norton 

 Maryland Ageicdltijral Experiment Station, 

 College Park, Md. 



SCIENTIFIC BOOKS 



The Electron, Its Isolation and Measurement 

 and the Determination of Some of Its Prop- 

 erties. By E. A. Millikan. University of 

 Chicago Press. 



This volume of 260 pages contains an ac- 

 count of the work on the exact determination 

 of the electronic charge and allied subjects 

 done by Professor Millikan and bis pupils 

 during the last ten years. It also contains an 

 account of the earlier researches which led up 

 to Millikan's work, and besides a short dis- 

 cussion of recent views on the electron theory 

 of matter and the theory of radiation to which 

 Millikan's exact investigations have added 

 precision in several important ways. 



The book is intended for tbe general reader 

 as well as for the physicist and it will be read 

 by both with immense enjoyment and instruc- 

 tion. It. is written clearly and concisely and 

 is full of most interesting and important in- 

 formation. 



The only criticsm the writer of this review 

 has to make is that the concluding chapters 

 are too short; they contain so much that is 

 interesting and suggestive that one can not 

 help wishing the writer bad found time to 

 make them as full of detail as some of the 

 earlier chapters. 



Millikan's beautiful investigations on tbe 

 electronic charge and on the photo-electric 

 effect are justly celebrated throughout the 

 scientific world; they will undoubtedly become 

 classical e.xamples of the highest type of 

 modem physical research. A description of 

 such researches by their author is immensely 

 valuable and will serve to stimulate scientific 

 investigation as nothing else can. 



Every student of physics, and especially 

 every graduate student, should obtain this 

 book and study it thoroughly and then en- 



