I L L U S T R A T I N S 



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 Fig. 1. Stem tumors on an old apple tree at ]Mesilla Park, N. Mex 6 



2. Stem tumors on a Meech quince tree at Chico, Cal 7 



3. Young tumors forming at the base of twigs on a Charlamoff apple 



tree at Fayetteville, Ark 8 



4. Older tumors than those shown in figure 3 on a Charlamoff apple 



tree at Fayetteville, Ark 9 



5. Roots produced from a tumor on a cutting taken from a Charlamoff 



apple tree and kept in moist soil 10 



6. Roots produced from tumors on a cutting taken from a Meech quince 



tree near Chico, Cal 10 



7. Longitudinal section of a tumor on an apple limb after throwing out 



roots when placed in soil 11 



S. Longitudinal section of woolly-knot on a root-grafted apple tree 



grown from apparently healthy scion and root 11 



■9. The woolly-knot form of hairy-root on a Northern Spy apple tree 



grown in an experiment 12 



10. The simple form of hairy-root on an apple seedling grown in an 



experiment 13 



11. The origin of hairy-root from buds on an apple seedling 13 



[Cir. 3] 



4 



