XIV Journal of Agricultural Research voi.x 



Page 



Fig. 4. Graph of toughness tests of artificially graded sand mortar 270 



5. Curve of toughness tests of artificially graded sand mortar 271 



6. Curve of toughness tests of natural concrete sand mortar 271 



7. Graph of tension tests of artificially graded sand mortars 272 



8. Graph of compression tests of artificially graded sand mortars 272 



9. Curv^e of tension tests of artificially graded sand mortars 273 



10. Curve of compression tests of artificially graded sand mortars 273 



Volatility of ORGAmc Compounds as an Index oP the Toxicity of Their 

 Vapors to Insects 



Fig. I. Volatility in gram-molecules evaporating in 400 minutes and the 

 toxicity in millionths of a gram-molecule killing insects in 400 

 minutes 3^7 



2. Continuation of figiu-e i, shovdng less volatile compounds 367 



3. Volatility and toxicity of the slightly volatile compounds on a larger 



scale than in figure 2 368 



4. Comparison of the volatility and toxicity of the acids 368 



5. Comparison of the volatility and toxicity of the esters 368 



6. Comparison of the volatility and toxicity of the halogen derivatives. . 368 



7. Comparison of volatility and toxicity of the hydrocarbons 369 



The Cyclamen Mite 



Fig. I. Map of the United vStates, showing distribution of Tarsonemtis pallidus 



Banks, the cyclamen mite 375 



2. Tarsonemus pallidus: A , long tactile bristle and large clavate organ be- 



tween the first and second legs; B, tarsus of foreleg of the female; 



C, posterior leg of male 376 



3. Tarsonemus pallidus: Ventral view of female larva 379 



4. Tarsonemus pallidus: Female quiescent larval stage with development . 380 



5. Tarsonemus pallidus: Adult female 38 1 



6. Tarsonemus pallidus: Adult male 382 



Relation of Movement of Water in a Soil to its Hygroscopicity and 



Initial Moistness 



Fig. 1. Graphs showing the penetration of i inch of water in soils A, D, H, and 

 M, each in three moisture conditions — viz, with a moisture content 



of 0.5, i.o, and 1.5 times the hygroscopic coefficient 417 



2. Graphs showing the rise of water in soils A, D, H, and M, each in three 

 moisture conditions — viz, with a moisture content of 0.5, i.o, and 1.5 

 times the hygroscopic coefficient 423 



Quassia Extract as a Contact Insecticide 



Fig. I . Graph showing the percentage of extract obtained by repeated soaking 

 of 10 gm. of quassia chips with 500 c. c. of water for 2 and 24 hours, 

 respectively 504 



2 . Graph showing the percentage of extract obtained by boiling 10 gm. of 



quassia chips with 500 c. c. of water for >^, 1,2,4,8, 16, and 24 hours, 

 respectively 505 



3 . Graph showing the influence of the state of fineness of the quassia chips 



upon the percentage of extract obtained when extracting 10 gm. with 



500 c. c. of water for 24 hours 506 



