SCIENCE^ADVERTISEMENTS 



Marine Biological Laboratory 



Woods nole» Mass. 



INVESTIGATION 



Entire Year 



INSTRUCTION 



July 3 to Auffuit 13, 

 1918 



Facilities for rescach in Zoology, 

 Embiyology, Physiology and Bot- 

 anj^. Seventy-six private labora- 

 tories, SlOO each for not over three 

 months. Thirty tables are avail- 

 able for beginners i n research who 

 desire to work under the direction 

 of members of the staff. The fee 

 for such a table is $50.00. 



Courses of laboratory instiuction 

 with lectures are offered in Inverte- 

 brate Zoology, Embryology, Physi- 

 ology and Morphology and Taxo- 

 nomy of the Algae. Each course 

 requires the full time of thestudent. 

 Fee, $50. A lecture course on the 

 Philosophical Aspects of Biology 

 and Allied Sciences is also offered. 



Animalaand plants, preserved, liv- 

 i ng, and i n embryonic stages. Pre- 

 served material of all types of 

 animals and of Algae, Fungi, Liver- 

 worts and Mosses furnished for 

 classwork, or for the museum. Liv- 

 ing mateiial furnished in season 

 as ordered. Price lists of Zoological 

 and Botanical materia 1 sent on ap- 

 plication. State which is desired. 

 For price lists and all information 

 regarding material, address 



GEO. M. GRAY, Curator, Woods Hole, Mass. 



The amiualannouncement willbe sent on application to The 

 Director, Marine Biological Laboratory. Woods Hole, Maes. 



SUPPLY 



DEPARTMENT 



Open the Entire Y«er 



Northrup Millivolter 



Made under the Pyrovolter Patent, 

 of November 6, 1917 

 The new NORTHRUP MILLIVOLTER is a 



standardized portable deflection potentiometer, 

 worlcing on the Pyrovolter Principle. 



This instrument offers a convenient means 

 for the accurate measurement of e m.f.s up to 

 one volt, without the abstraction of any current 

 from the source of the e.m.f. being measured. 



The MILLIVOLTER should generally be 

 used in place of a millivolter, where accuracy 

 is of importance. It is valuable for taking the 

 voltage drop in motors, for the measurement of 

 low voltages over electrolytic baths where a 

 carefully measured current is flowing, for use in 

 thermocouple pyrometry, for measuring the in- 

 ternal resistance of dry cells, and for accurate 

 measurement of large currents by reading the 

 voltage drop over a low known resistance. 



The MILLIVOLTER has one hand-drawn 

 scale and three ranges: o-io mv., o-ioo mv., 

 and o-iooo mv. It is described in Circular No. 

 9, which awaits your request. 



Pyrolectric Instrument Co, 



Pyrometrlc and Electrical Preciston 

 Instruments 



US E. State St. Trenton, N. J. 



OPTIC PROJECTION 



Principles, installation and use of the Mag'o Lantern, Opaque 

 Lantern, Projection Microscope and Moving Picture Machine; 

 TOO pages, 400 figs. By Simon Hbnkt Gage. B.S., and 

 HsamT Phelps Gaqb, Ph.D. Postpaid, $3.00. 

 THE COMSTOCK JPUBUSHING CO., Ithaca, N.Y. 



Memoirs of the Wistar Institute of Anatomy and 

 Biology. No. 6, 1915 



THE RAT 



Data and Reference Tables. 278 Pages. 89 Tables. 



Bibliography. 

 Compiled and Edited by HENRY H. DONALDSON. 



Postpaid $3.00. 



The Wistar Institute 



Philadelphia, Pa. 



Philadelphia House for Sale 



In West Philadelphia, near the 

 University of Pennsylvania, stone 

 house on corner, 30 ft. front, four- 

 teen rooms and two baths. Price, 

 $14,000. Apply to Wm. H. W. 

 Quick & Bro., Inc., 8 South 

 Fortieth St., Philadelphia, Pa. 



Cooking Class at the 

 Sotttli Dakota State College 



axe using gas made by 



The "Detroit" 

 Combination Gas Machine 



for supplying gas in Departments of 



Domestic Science 

 Chemistry and Physics 



(Over 30,000 in daily cse) 



Laboratory work can be done better, 

 quicker and cheaper by using this gas. 

 Ask for descriptive catalog and names 

 of users in your vicinity. 



Detroit Heating & Lighting Co. 



612 Wight St. Detroit, Mich. 



Elt. 1868 



