354 BACTERIAL DISEASES OF PLANTS 



pricking each several times with a deUcate needle infected from 

 young potato or agar-streak cultures. Leaves should be inocu- 

 lated in the midrib or main veins as well as in the parenchyma. 

 Small trees suitable for inoculation may be obtained from 

 nurserymen and planted in the autumn for late spring inocu- 

 lations out of door, or in the hothouse for inoculations in late 

 winter and early spring, whenever shoots are pushing. 



Determine 



For the organism. Morphology. — Size in microns (diam- 

 eter is more important than length, but that also should be 

 recorded, examining both young and old cultures on various 

 media). Conditions under which chains are formed. Ditto 

 pseudozoogloeae. Ditto involution forms (use peptonized beef 

 broth with 6 per cent sodium chlorid). Motility (on margin 

 of a hanging drop). Number and attachment of flagella (use 

 Pitfield's stain). Ethel M. Doidge in South Africa, finds 

 1 to 4 polar flagella (Fig. 272 A). In my first studies of the 

 Georgia organism I saw only 1 to 2 polar flagella, but slides 

 stained for me in 1915 by Mary Katherine Bryan, using the 

 French organism and van Ermengem's silver-nitrate stain, show 

 1 to 7 polar flagella on backgrounds very free from detritus 

 or artefact lines (Fig. 273). Absence of endospores (heat, spore 

 stains), existence or non-existence of a capsule (Ribbert's dahlia 

 stain) . Reaction to various other stains including Gram's stain, 

 and acid-fast stain. 



Cultural Characters. — Appearance in poured plates of +15 

 peptone beef agar (Figs. 274, 275), streaks and stabs. Ditto -t-10 

 beef peptone gelatin. Growth on Loffler's solidified blood serum 

 (the streak should be flat, white, smooth and glistening). Is 

 there any liquefaction of gelatin or solidified blood serum? 



Behavior on potato cylinders. Test, when growth has ceased, 

 for destruction of starch. 



Appearance in +15 peptonized beef bouillon. Action, if 

 any, on potassium nitrate in peptonized beef bouillon. Beha- 

 vior in milk and litmus milk (watch very carefully the early stages 

 for absence of coagulation and acidity and the late stages for 



