SCIENCE-ADVERTISEMENTS 



Just Issued 



KOFOID and SWEZY 



Mitosis and fission in the active and encysted 

 phases of Giardia enterica (Grassi) of Man. 

 50 cents. 



Mitosis in Endamoeba dysenteriae in the bone 

 marrow in Arthritis deformans. 



Endamoeba dysenteriae in the lymph glands 

 of Man in Hodgkin's disease. 



In one cover, 25 cents. 



Mitosis in the encysted stages of Endamoeba 

 coli (Losch). {In press), 30 cents. 



University of California Press 



Berkeley, California 



Research Prize of $1,000 



The Ellen Richards Research Prize 

 is offered for award in the year 1 923. 

 Theses by women based on indepen- 

 dent laboratory research are eligible 

 for competition and must reach 

 the Committee before February 25, 

 1923. 



For circulars of information and 

 application blank, apply to 



DR. LILIAN WELSH, 

 Goucher College, Baltimore, Maryland 



For further information apply to 

 the Secretary, Mrs. Samuel F. Clarke, 

 Williamstown, Mass. 



For Demonstrating and Detecting 



ive 



Hammer's Spinthariscope 



is a device to illustrate 

 the spontaneous disinteg- 

 ration of radium. Alpha 

 rays expelled from radium 

 ore strike a screen of 

 phosphorescent zinc sulphide causing bril- 

 liant flashes of light which can be observed 

 through a high-powered magnifying glass. 



Price complete as shown $4.00 



Phosphorescent zinc sulphide screens 



4" X 4" each 2.00 



Hammer's Radioscope 



is an instrument for 

 detecting the presence 

 o f radio-activity in 

 water, ores, etc., by 

 the scintillation meth- 

 od, which is the most 

 sensitive of all meth- 

 ods for determining 

 the presence of ra- 

 dium. 

 Price complete, $10.00 



Headquarters on Radium Apparatus 

 For Sale by 



The Denver Fire Clay Company 



Denver, Colorado !eS3I ^^** Lake City, Utah 



