1 32 FUNGOUS DISEASES OF PLANTS 



The bacteria invade the intercellular spaces of the host, and 

 subsequently the tissues are rapidly disorganized. This disorgani- 

 zation is apparently due to an enzyme which attacks particularly 

 the middle lamella. A large number of inoculation experiments 

 have been made, and it is clearly shown that these bacteria are 

 able to produce a form of soft decay in a great variety of plants. 

 No other organism yet found has such a wide range of host plants. 

 Morphology and cultural characters. The bacillus is in the 

 form of short or long rods or chains. According to Jones it 



measures .6 — 09 x 1.5-5 /"■, tne major- 

 ity, however, measuring .8X2/x. No en- 

 dospores are produced, and it possesses 

 from two to ten peritrichiate flagella. 



Upon slanting tubes of agar an abun- 

 dant growth is produced. This is fili- 

 form to spreading, smooth or contoured, 

 and opaque to opalescent in appear- 



FlG. 18. Bacillus cirotovorus t , , ,i 



T J ...„ T D t , ance. It also grows well on potato. 

 Jones. (After L. R. Jones) & r 



Gelatin is promptly liquefied, under 

 ordinary circumstances, at 20 C. Usually liquefaction begins on 

 the second day and is complete in six days ; yet months may be 

 required. In bouillon a pellicle is often formed. In other cases 

 there is merely a clouding, or finally the development of a floccu- 

 lent precipitate. Milk is usually coagulated by the third day, and 

 this is so slowly peptonized that the action may not be complete 

 for several months. Litmus milk is rendered acid, and the power 

 of indol production is possessed to a feeble extent. 



The organism reduces nitrates in nitrate broth to nitrites. The 

 thermal death point is about 48 to 50° C. It is also important to 

 note that with a majority of the strains gas is produced in small 

 amounts with dextrose, lactose, and saccharose. In this gas- 

 producing character the forms of the organism from a large 

 number of sources show a certain variation, however, which 

 reaches an extreme in the form producing soft rot of the calla 

 lily, in which case no gas is produced from any of the sugars 

 mentioned. The calla lily organism is tentatively retained as a 

 distinct species. It represents, at any rate, an extreme form of 

 the Bacillus carotovoncs so far as it is at present known. 



