Two Cambosco Instruments 



32-254 TRANSPIRATION App. 

 Detmer P. 214. 



Garr call's 



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 amiount of transpiration 

 depends upon the degree of moisture in the 

 air and that a rising temperature accelerates 

 32-254 transpiration. The m/e of transpiration in ^r^' 32.256 



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 Plant World 



Established 1884 



LIGHT FILTERS 



We are able to supply a series of glass screens which absorb or transmit various 

 parts of the spectrum and are useful for experimental work in growth, photo- 

 tropism, and photosynthesis. These glass screens were developed by Dr. D. T. 

 MacDougal, and are now available in bell-jars 36 x 36 cm. in size, with perforated 

 top, or in plates 16.5 cm. square. 



Red Plates. A good monochrome transmitting to .610 u $1.50 each 



Blue Plates. Transmitting wave lengths less than .510 u SI. 50 each 



Orange Plates. High transmission in red and green to .530 u. 



Bridges the spectrum from red to blue ' -$1.00 each 



Heat-Absorbing Plates. Absorb most of the infra-red and 97% 

 of the heat of a Nernst lamp. Give a pyrhehometer reading 

 about half that of good window glass. Transmit 65% of inci- 

 dent white light. In plates only SI 00 each 



Uviol Plates. Transparent to visible spectrum, transmitting 

 ultra-violet to .310 u. in sheets 6 mm. thick to .300 u. in 

 sheets 3 mm. thick. In plates only SI. 00 each 



Terms for bell-jars furnished on request. Additional information 



cheerfully given 



THE PLANT WORLD TUCSON, ARIZONA 



