1919I ROSE— BLISTER CANKER 137 



2 were analyzed according to a method devised by Kraybill 

 (unpublished work) in a study of the chemical composition of tomato 

 plants. Material for 4 of the samples, healthy i and 2 and diseased 

 I and 2, was taken from 8-10 cm. apple limbs cut in January at 

 the Missouri State Fruit Experiment Station, and shipped from 

 there by express. As soon as these samples arrived they were pre- 

 pared as follows: bark designated as "healthy" was removed from 

 sound limbs with a box scraper and cut into pieces half an inch 

 square; about 150 gm. were then weighed quickly on a torsion bal- 

 ance to hundredths of a gram and put into enough redistilled alcohol 

 (95 per cent) to give an alcohol concentration of approximately 

 85 per cent. The bottles containing the samples were then set 

 into a steam bath until the alcohol came to a boil, then on top for 

 I hour longer, to inactivate the enzymes. 



Bark designated as "diseased" was taken from 8-10 cm. 

 limbs showing well developed but not old cankers, usually about 

 45 cm. long. A strip of moist browned bark 2-3 cm. wide around 

 the outside of the canker was removed with the box scraper, 

 cut up, weighed, and preserved as described. This material usually 

 contained small portions of the seemingly healthy bark outside 

 of the canker, but never any part of the black dead material that 

 often covers the central part of the cankered areas. Healthy 

 samples 3 and 4 were taken from a 7 cm. limb cut in April when 

 the bark peeled easily, to avoid removing small shavings of wood 

 along with the bark, as was inadvertently done in the case of healthy 

 samples i and 2 (see discussion of table XXV) . Healthy samples 3 

 and 4 were not extracted with hot alcohol and ether as in the 

 method described by Harvey (21); instead the alcohol for pre- 

 serving was filtered into a 1000 cc. flask and made up to volume. 

 One-twentieth aliquots were then pipetted off into small beakers, 

 evaporated to a syrup, and used later for dry weight and other 

 estimations. The partly extracted bark was dried as described 

 for the other samples, weighed, ground, allowed to come to air dry 

 condition, and one-twentieth aliquots weighed out as before. 

 This method of handling the material is much shorter than the 

 Koch method and is very satisfactory if one is not interested in the 

 distribution of substances in the various fractions. 



