240 BACTERIAL DISEASES OF PLANTS 



Wormald in England has described a schizomycete which at- 

 tacks celery producing a soft-rot (Figs. 49 and 185) but is not 

 active on potato shoots (Fig. 186). This, he is now inclined to 

 think, is also identical with Bacillus carotovorus, but I am in 

 doubt and shall keep it separate for the present. 



Very closely related forms are Bacillus aroideae Townsend 

 (Fig. 187) on calla lily and Bacillus melonis Giddings on musk- 

 melon. Townsend's organism differs in the form of its colonies 

 on agar (they are, however, like those shown in Fig. 177) and 

 in some of its fermenting powers, i.e., acid without gas from 

 dextrose, lactose, saccharose and mannit. Its effect on raw 



FIG. 182. Buried colonies of Bacillus carotovorus in +10 beef-peptone gelatin 

 plates after 24 hours at 18C., showing colorless root-like extensions. The several 

 small dark spots ringed with light are due to irregularities in the gelatin or to 

 dirt on the eyepiece. X 135 circa. 



carrot at the end of 8 days is shown on Fig. 188. Gidding's 

 organism produces abundant gas from milk (99 per cent. CO2) in 

 the closed end of fermentation tubes; liquefies blood serum; 

 does not produce gas with dextrose, saccharose, lactose, maltose 

 or mannit, and has a maximum temperature of about 45C. 



I think Bacillus aroideae and Bacillus melonis are identical. 

 At least an organism isolated by us from rotting calla lily and 

 identified as Bacillus aroideae produces gas in milk (Fig. 189). 

 With his original isolation (now lost) Dr. Townsend made no 

 tests in fermentation tubes containing milk. 



I have been inclined to think that Bacillus carotovorus and 

 Bacillus phytophthorus are not strictly identical, and have kept 



