32 Control of the Greenho^tm White Fhf 



REFERENCES. 



(1) QuAiNTANCE, A. L. and Baker, A. C. (1913-14). U.S. Dept. Agric, Bur. Ent., 

 Tech. Ser. No. 27. 



(2) Morrill, A. W. and Back, E. A. (1011). U.S. Dept. Agric, Bur. Ent., Bull. 

 No. 92. 



(.3) Hargreaves, E. (1915). Ann. App. Biol, i, Nos. 3 and 4. 

 (4) Williams, C. B. (1917). Journ. Genet, vi. No. 4. 

 (o) ScHRADER, F. (1920). .Joum. Morph. xxxiv, pp. 267-30.5. 

 (fi) Sasscer, E. R. and Borden, A. D. (1917). U.S. Dept. Agric, Farmer.^' Bull. 

 880. 



(7) QuAYLE, H. J. (1919). Univ. California Public, Bull. 308. 



(8) SciiOENE, W. J. (1913). New York Agric Exp. Stat., Bnll. 30. 



EXPLANATION OF PLATES I AND II. 



PLATE I. 



Fig. 1. Underside of leaf of zonal geranium showing circles of eggs of A. vaporariorum. 



Fig. 2. A. sonchi Kotinsky, on Sonchus oleraceus in a Lea Valley tomato house. 



Fig. 3. Three tomato plants cyanided side by side and photographed a fortnight after 

 the fumigation. The hard plant was not damaged while the two soft plants show a 

 severe scorch and crinkle of the foliage, the damaged leaves continuing to function 

 jiartially. The plants are growing away from the damage. 



PLATE II. 



Two tomato plants photographed immediately before (Figs. 4 and 6) and a week after 

 (Figs. 5 and 7) cyaniding together, J oz. cyanide per 1000 eft., duration 9 hours, 

 temperature 60-54° F., relative humidity 97 per cent. Fig. 4 represents a plant well 

 watered and turgid, and the severe damage it received from the gas is shown in Fig. 5. 

 Fig. represents a plant which was not flaccid but required water, and Fig. 7 shows 

 that it was undamaoed. 



{Received July 27th, 1921.) 



