PLATE 40 



Exterior view of isolated room in the pathological greenhouse at the University of 

 Wisconsin, showing (a) the exterior portion of air- washing apparatus used to wash all 

 air drawn into the room, (b) the canvas curtain used for shading on warm days, and 

 (c) the sprinkling attachment used to throw spray of water over the roof to aid in 

 keeping the room cool. (See fig. i and description of apparatus in text.) 



A. — Greenhouse with canvas curtain rolled up. 



B. — Greenhouse with canvas ctu-tain rolled down. 



