SCIENCE-ADVERTISEMENTS 



THE OESTROUS CYCLE 

 IN THE RAT 



And Its Associated Phenomena 



By 



Long and Evans 



14S pages, II plates, 7 figures in text; paper, $3.75 



The profound importance of an infallible 

 method of detecting in the IMammalia the periodic 

 function of the ovary, and the possibility, through 

 the possession of such a method, of the investiga- 

 tion of disturbances of the ovarian function are 

 matters of interest to students of the subject. 

 Before proceeding to such investigation, it would 

 be necessary to establish clearly all the charac- 

 teristics of what has been called the normal 

 oestrous or reproductive cycle in the animal chosen 

 for investigation. To that task the present mono- 

 graph is devoted. 



University of California Press 



BERKELEY, CALIFORNIA 



AMERICAN JOURNAL OF BOTANY 



Devoted to All Branches of Botanical Science 



Establislied 191A. Monthly, except August and September. 

 Olncial Publication of the Botanical Society of America. 



Subscription, $6 a year. Volumes 1-S complete, $58 

 post free. Single numbers, 75 cents, post free. Prices of 

 odd volumes on request. 



Foreign postage: To Canada, 20 cents; to other coun- 

 tries, 40 cents. 



Devoted to All F 



Established 1920. 



Official Publication of thi 

 Subscription, $4 a year. ] 



ECOLOGY 



s of Life in Relat 



to Environment 



Quarterly. 

 Ecological Society of America. 

 .ck volumes 1-3, $3.50 post free. 



Single numbers, $1.15 post free. 

 Foreign postage: To Canada, 10 cents; to other coun- 

 tries, 20 cents. 



GENETICS 



A Periodical Record of Investigations in Heredity and 

 Variation 



Established 1916. Bimonthly. 



Subscription, $6 a year. Single numbers, 51.15 .post free. 



Foreign postage: To Canada, 25 cents; to other coun- 

 tries, 50 cents. 



BROOKLYN BOTANIC GARDEN MEMOIRS 



Volume One contains 33 contributions on genetics, 

 pathology, mycology, physiology, ecology, plant geog- 

 raphy, morphology, and systematic botany. 



3S plates, 41 text figures. 



Price $3.50 plus postage. Weight, 4 pounds. 



Published irregularly. 



Orders should be placed direct with 



The Secretary, Brooklyn Botanic Garden, 

 BROOKLYN, N. Y., U. S. A. 



HIGH VACUUM PUMPS 



Whenever in lecture-room or laboratory practice, really high 

 vacuum is required, we recommend the Condensation Pump devel- 

 oped by Dr. Irving Langrauir of the General Electric Company— believ- 

 ing it to be superior to any other as yet obtainable. 



The Langmuir Pump operates with surprising rapidity, and 'there 

 seems to be no practical limit to the degree of exhaustion that can be 

 produced. 



Some form of auxiliary pump nmst be used; and for that purpose 

 we offer a special G.E. two-stage oil-sealed mechanical pump, which 

 is capable of producing a vacuum of 

 o.ooi mm. when used alone. 



The picture shows a complete out- 

 fit comprising Langmuir Condensation 

 Pump, two-stage, auxiliary pump and 

 Vz H.P. motor — all mounted together on 

 one base. 



Write for descriptive bulletin S-965 



j JAMES G. BIDDLE 



1211-13 Arch St. , Philadelphia 



