246 BACTERIAL DISEASES OF PLANTS 



the organism stain by Gram? Jones says it does, Harding 

 and ]\Iorse say it does not. Examine always with the substage 

 diaphragm wide open. For comment on use of Gram's stain 

 see "Bacteria in Relation to Plant Diseases," Vol. I, page 188. 

 Is it an acid- fast organism? Presence or absence of involution 

 forms (examine 2 -months-old cultures on steamed carrot 

 and read what Jones says on page 314 in his first English paper). 

 Try also much younger cultures in 1 per cent dextrose peptone 

 water. Any Y-shaped or branching forms? Make cultures 

 in bouillon containing 4 to 10 per cent of ethyl alcohol and 

 search for the coccus-like forms which Wormald has described 

 and figured for Bacillus apiovorus in "The Celery-rot bacillus." 

 {The Jour. Agr. Science, Vol. VIII, Pt. II, March, 1917). 



Cultural Characters. — Determine behavior on thin-sown agar- 

 poured plates, also in agar-streak cultures and stab cultures. 

 In thin-sown gelatin-poured plates study (on the first, second 

 and third days) the buried and the fimbriate-margined surface 

 colonies with medium magnifications. Determine rate of 

 liquefaction in gelatin stab cultures; behavior of streak cultures 

 on Loefiler's solidified blood serum, on solidified egg albumen; 

 curdling effects in milk and litmus milk; growth on steamed 

 potato cyUnders and carrot cylinders; behavior on the surface 

 of raw potatoes in contrast to surface of raw carrots. Do you 

 find any marked difference? Inoculated raw apple and raw 

 turnip will afford another interesting comparison. If there 

 is time, a whole series of raw fruits and vegetables (thick slices 

 in deep Petri dishes) should be inoculated. Results cannot be 

 compared, of course, unless the temperatures are the same. 



Growth in -f-15 peptone beef bouillon should be compared 

 with that in salted peptone water (Dunham's solution), and 

 in various synthetic media, e.g., Cohn's solution (no growth), 

 Uschinsky's solution (abundant growth), Fermi's solution, etc. 



Contrast with B. phytophthorus in Soyka's milk-rice. The 

 one culture (3a) should be yellowish, the other, pinkish. 



Behavior in good fermentation tubes in peptone water 

 containing various sugars and alcohols. With which is there 

 clouding in the closed end? With which gas formation ? What 

 is the composition of this gas? At least some simple experi- 



