32 PLANT PHYSIOLOGY 



It is no part of my present subject to describe these houses, but 

 if the teacher cares for such information, he may find the com- 

 plete Smith College equipment (the Lyman Plant-house, a 

 memorial gift) described in Science, 15, 1902, 933. 



The experiment greenhouse has the form and arrange- 

 ment shown by figures 2, 3, 4, and by the accompanying photo- 

 graphs, Plates I and II. It is 32 by 19 feet,* inside measure, 

 with solidly founded brick walls rising 3 feet 6 inches from the 

 floor, above which are glass sides to 6 feet, while the glass roof 

 rises in the center to 12 feet 6 inches. Ample ventilators are 

 provided on walls and roof, and care is taken that the venti- 

 lator rods do not project into the room beyond the walls. The 

 floor is everywhere cemented, and no special arrangement for 

 drainage is needed, since evaporation and occasional mopping 

 accomplish this result. The heating (hot-water) pipes, fully 

 controllable by valves, are ten, of 2^-inch diameter, arranged 

 along the walls as shown in figure 4, but include four more 

 in number than are needed. Upon the pipes are shallow trays 

 of galvanized iron, kept filled with water, which helps to moisten 

 the air; but on dry, warm days these must be supplemented 

 by copious sprinkling (by hose) of the cement floor. In this 

 feature, however, the house could be improved, and I have no 

 doubt it would be better if the pipes were sunk below the floor 

 in brick or cement pits (covered by iron gratings), so arranged 

 that water could constantly evaporate from them; upon occa- 

 sion, additional moisture could be quickly provided by spray- 

 ing the pipes themselves. 



So much for the house itself, which, as a whole, is most 

 satisfactory in use. We consider next its furnishings. 



First are the tables, which must be very solidly built in order 

 not to move when touched or pushed. They are in number 

 as shown by figure 2, are 3 feet high (the best for work while 



* That I use feet and inches for laboratories and furniture, while keeping to the 

 metric system for all scientific measurements, is due neither to oversight nor lack 

 of desire for universal extension of the metric system, but to the feeling that it is 

 the most convenient and sensible way under present conditions. 



