LIGHT FILTERS 



We are able to supply a series of g^ass 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 SI. 00 each 



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

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

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

 dent white light. In plates only SlOO 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 $1.00 each 



Terms for bell-jars furnished on request. Additional information 



cheerfully given 



THE PLANT WORLD TU.CSON, ARIZONA 



A MAP OF THE 

 VEGETATION OF THE UNITED STATES 



A colored map 20 x 12 inches in size showing the 18 major types of vegetation 

 in the United States. Prepared by Di. Forrest Shreve, and reprinted from the 

 Geographical Review. Accompanied by a brief descriptive text. 



Text, with Folded Map $.50 each, $4.00 per ten 

 Text, with Rolled Map $.60 each, $4.10 per ten 



THE PLANT WORLD Tucson, Arizona 



KODAK FINISHING 



We Guarantee to get the best possible results from your 



exposures. Mail orders attended to promptly. 



Catalogue and Price List Free 



The Smith Sporting Goods Company 



TUCSON, ARIZONA 



