SCIENCE— ADVERTISEMENTS 



A Rubber Plant Survey 



of 



Western North America 



By Harvey Monroe Hall and 

 Thomas Harper Goodspecd 



I. Chrysothamnus Nauseosus and its Varieties. 



Harvey Monrde Hall. 



II. Chrysil, a New Rubber from Chrysothamnus 

 Nauseosus. Harvey Monroe Hall and 

 Thomas Harper Goodspeed. 



in. 



The Occurrence of Rubber in Certain West 

 American Shrubs. Harvey Monroe Hall 

 and Thomas Harjper Goodspeed. 



278 pages. 



3 plates. 8 figures in text. 

 $1.25 



The University of California Press 



Berkeley, Calilornia 280 Madison Ave, New York 



For colleges desiring an elementary 



course. 

 For such sections of students in large 



colleges as have not had chemistry 



in School. 

 For normal schools and technical high 



schools. 



Mcpherson and Henderson 

 Elementary Study of Chemistry 



Second Revised Edition 



Thorough on the principles. 



Illuminating in the explanation 

 of industrial phases of the subject. 



Amply equipped with pictures 

 and the best of diagrams. 



Written in a clear and effective 

 style. 



GINN AND COMPANY 



70 Fifth Avenue 

 New York 



Spencer Scientific Instruments 



WHETHER 



Microscopes, Microtomes, Delineascopes 

 Refractometers and other Apparatus 



MAKEjAN INSTINCTIVE APPEAL 

 TO THE LABORATORY WORKER 



It isn't only their accuracy and utility. It's something in the finish even 

 more in the design but in addition to all these, it is those little things — 

 clever little devices, which accomplish the same end but in a better way — 

 exactly the wa}' that the laboratory worker wants them. These are ten dis- 

 tinctive features of Spencer Instruments, made distinctive because our de- 

 signers, experienced laboratory workers, possess the laboratory view point. 



Spencer Microscope No. 44 



To oui way of thinking, is the most beautiful microscope for general labora- 

 tory purposes ever made. Set it alongside any other and see if our verdict 

 is not correct. From efficiency and utility standpoints, it also has advan- 

 tages. Fully equipped with oculars 6x and lOx, triple nose piece, objectives 16 mm., 4 mm. and 

 1.8 mm. immersion. Abbe condenser with iris in quick-screw substage, in cabinet j^llO.OO. 



1920 Catalogue Now Ready 



^ai^ SPENCER LENS 



BUFFALO, N. 



