Drying Roots of Seedlings. 313 



is at times overlooked. The drier the air, the more rapid the 

 evaporation. 



As to the wind, it is an elementary principle of physics that 

 rate of evaporation is increased by increased movement of air 

 over the body from which the evaporation occurs. The in- 

 fluence of wind direction would probably be included under other 

 factors. It might influence humidity, temperature, precipitation, 

 velocity. In the present instance, the south wind is apt to be 

 warm, and perhaps, moist, though not markedly so. 



The exposures were made on pine planks. This is prob- 

 ably a severer test than it would be to leave them on the ground 

 as would probably happen in practice. 



As suggested above, the plants may be either replanted or 

 packed for shipment after exposure. In some cases the roots 

 are puddled whether for shipment or transplanting. In the 

 present experiment all the exposures in a series w^ere started 

 at the same time the successive lots being stopped at different 

 times and placed with the roots in wet sphagnum in the pack- 

 ing shed until evening, when all were planted after sunset. It 

 has been suggested that perhaps the wet moss had a tendency 

 to revive the exposed plants, but it is the treatment they would 

 receive if shipped to a customer. From the standpoint of im- 

 mediate transplanting it might have been better to start the ex- 

 posures at dift'erent times, and stop them all at once, transplant- 

 ing immediately. It was, however, desired to plant after sun- 

 set to reduce, as much as possible, untimed harmful exposure, 

 and to use the method suggested would have involved continu- 

 ing the exposure for a time (an hour or two or half an hour, 

 perhaps) after the sun at least, and possibly the wind had con- 

 siderably declined in destructive effects. True, commercially, 

 plants would never be planted at night, but it is' believed the 

 treatment adopted eliminated some variables difficult to de- 

 termine. 



To avoid having so many plants that the handling would lack 

 precision because of mere numbers, but two species (Pinus strobus 

 and Pinus resinosa) were used, and only three year seedlings 

 of these, two of each kind to each set. Even so the results show 

 a considerable variation. The individuals used were not chosen, 

 but taken as they came from the bed. 



