108 CREKNITOl'SE Fl'M MIATIDX 



Moisture on the leaves aids the gas to ])enetrate, l)tit is not so 

 important a factor where the hotise contains (inl\- plants with thick, 

 heavy cuticles. 



Moisture may he ])resent on the leaxes, from sprinkling- the 

 l)lants or from exudation of water from the water pores. 



High relative humidity at the time of fumigation aids the pene- 

 tration of the gas through the cuticle, thus favoring- injur}-. 



High relatixe humidity after fumigation tending to prevent 

 evaporation of hydrocyanic acid in the cuticle of the ])lant tends 

 to increase injury to the ])lants. 



Low temperatures at the time of fumigation and after acts in 

 a similar nianner to a high relative humiditv. 



lligh temperature by increasing- evaporation ])roduces results 

 similar to a low relatiAe humidit}-. 



iloth high relatixe humidit}- and low temperature have less 

 influence on plants ^vith thick, wax\' leaxes. 



LITERATURE CITED. 



1. Woods and Dorsett. The Osc of Hydrocyanic Acid Gas for Fumigating 

 Greenhouses and Cold Frames. U. S. Dept. of Agr.. Circ. 37, 1899. 



2. Stone, G. F. The Influence of Various Light Intensities and Soil Mois- 

 ture on the Growth of Cucumbers, and Their Susceptibility to Burning 

 from Hydrocyanic Acid Gas. Mass. Exp. Sta., 25th .\nn. Rpt., 1913. 



3. Llovd, F. I-".. Tile Physiology of Stomata. Carnegie Inst., Wash., Pul). 

 82, 1908. 



4. Pfert'er, W. The Physiology of Plants. Vol. I, Vm. 



5. Penntv, C. !.. The Diffusion of Hydrocyanic .\cid Vapor in an En- 

 closed Space. Del. Exp. Sta., 12th Ann. Rpt., 1900. 



6. Johnson, W G. Fumigation Methods. 1902. 



7. Woglum, R. S. Hydrocyanic Acid Gas F'umigation in California. \J. S. 

 Dept. of Agr. Bur. of Ento. Bull. 90, Part I. 1911. 



8. Tower, W. \'. I'umigation Dosage. Mass. Fxp. Sta. 22nd Ann. Rpt., 

 1910. 



