Nov. i, 1920 



Effect of Drying Disinfected Seed Wheat 



235 



formaldehyde fumes was not determined ; but according to Auerbach and 

 Barschall (2), the partial pressure of formaldehyde gas above solutions 

 in a closed space increases with the concentration of the formaldehyde 

 solution ; hence the fumes may be the cause of injury. 



Several experiments showed clearly the varying degrees of injury 

 resulting from drying the seed at different rates. The usual procedure 

 was to treat some wheat with a 0.2 per cent solution and some barley 

 with a 4.5 per cent solution, the latter being more resistant to drying 

 injury and therefore requiring the use of a strong solution to produce it. 

 Some of each lot was then spread thinly over towels on the laboratory 

 table, while the rest was put in an open tumbler or a slender, uncovered 

 bottle. For comparison, a third lot usually was placed in a similar 

 bottle. and sealed while damp. Samples were removed after various 

 intervals and were germinated in the usual way to determine the degree 

 of injury. The data on the germination of wheat are shown in Table XI 

 and those on the germination of barley in Table XII. 



Table XI. — Percentage of germination of Little Club wheat treated with 0.2 per cent 

 solution of formaldehyde and dried under different conditions and during periods of 

 varying lengths 



Wheat treated with a o. i per cent solution was dried overnight in a 

 sealed jar, in an open jar, and in a thin layer on towels. After drying 

 24 hours, equal samples were washed in equal volumes of water, and the 

 washings were subjected to Tollen's aldehyde test for the presence of 

 formaldehyde. Comparison of the density and rapidity of formation of 

 the silver precipitate showed that there was least formaldehyde on the 

 thinly spread seed and greater amounts on the other two samples. At 

 the end of the second 24-hour period the experiments were repeated. 

 It was found that the amount of formaldehyde on the sealed seed had 

 diminished until it gave a much less dense precipitate than either of the 

 dried samples. Of the latter, the extract from the seed dried in the 

 bottle showed the presence of more formaldehyde than that from the 



