Two Cambosco Instruments 



32-254 TRANSPIRATION App. Garreau's 

 Detmer P. 214. 



To determine the amount of transpiration 

 from the upper and lower sides of a leaf at 

 the same time. Complete, . . . $4.50 



32-256 TRANSPIRATION CHAMBER, 

 Detmer, P. 219. 



To show that the amount of transpiration 

 depends upon the degree of moisture in the 

 air and that a rising temperature accelerates 

 32-254 transpiration. The ra/e of transpiration in Jr^; 32.255 



air and in moist is easily determined. Without burner or thermometer, $5.00. 



SEE Botanical Catalog, 91, P. 49, for complete information. 



CAMBRIDGE BOTANICAL SUPPLY COMPANY 



M'AVERLEY, MASS. 



Leading American Makers of Physiological Apparatus 

 Laboratory Equipment for all the Sciences 



Catalogue Free Mention Blant World 



Established 1884 



SPHERICAL ATMOMETER CUPS 



A spherical evaporating surface, 5 cm. 

 in diameter, presenting the same external ex- 

 posure in all directions, with glazed cylindri- 

 cal neck 3 cm. long and 2 cm. inside diameter. 

 They are composed of very resistant material, 

 of proper porosity for atmometric work, and 

 are to be mounted on rubber stoppers as in 

 the case of cylindrical cups. The spheres may be cleaned with brush and distilled 

 water, may be treated with acid, and even heated to red heat. They should thus be 

 capable of many years of use, without permanent alteration of the coefificient. They 

 are not easily broken. 



These new spheres are supplied either standardized or unstandardized. Stand- 

 ardization is carried out with reference to a newly adopted spherical standard; spheres 

 cannot be satisfactorily standardized to the cyUndrical standard cup. Therefore 

 readings from spheres are not satisfactorily reducible to terms of readings from cylin- 

 ders (see Plant World, Vol. 18, pp. 21, 51, 95, 143). 



Unstandardized White Spheres, $2.25 each, $20.00 per ten 

 Standardized White Spheres, $2.75 each, $25.00 per ten 



THE PLANT WORLD 



TUCSON, ARIZONA 



