X/' of the. Tt<r,iip (IJrassica uapus). 455 



cell-wall* in the interior of the tissue, however, presented the normal 

 appearance, neither swollen nor readily separating. 



Control experiments were set up, in which, after four days, the 

 manometer and pyrogallic flask were disconnected, and the air allowed 

 to diffuse into the flasks ; upon subsequent examination the blocks in 

 these were found to have become completely rotten. We may thus 

 infer that the action of P. ilestntctans only proceeds so far as a supply 

 of oxygen is available. 



Potatoes as well as turnips were employed in these experiments, and 

 the results in each case were the same, except that with the potato 

 when the flask was connected with the pyrogallic flask and manometer, 

 immediately after the inoculation of the blocks, no bubbles of CO L > 

 were observed to escape round the bend, and there was no indication of 

 the rot. 



Character* of Pseudomonas Destructans. 



Ifn/'if. On growing turnips producing a " White Kot " in the living 

 tissues. 



Morphology. Short motile rods, 3 n x 8 p, with a single polar fla- 

 gellum. 



Culture* can only be made in the presence of oxygen. 



Gelatine.- -Petri Capsule*. Forms circular colonies of whitish-grey 

 liquefying gelatine. 



Sfal> Culture*. Grows rapidly along the track of the wire, 

 forming a funnel-shaped tube of liquid gelatine, with a white, 

 cloudy deposit in the liquid portion. 



A(ic. -White, glazy growth. 



Tamil*. Grows rapidly as a parasite. 



Potato awl Carrot. -Same effect as on the turnip. 

 . No growth as a parasite. 

 -Koch's bouillon and turnip ; becomes cloudy and opaque. 



Ferine-lit.*. A cytase, causing the swelling and softening of the cell- 

 wall, and dissolution of the middle lamella. 



A diastase. A peptonising ferment, producing liquefac- 

 tion of gelatine. 



Toxiit. Oxalic acid formed as a product of metabolism in turnip- 

 juice and in Pasteur's solution containing cane sugar. 



Stain*. Keadily stained with the ordinary aniline dyes, but not with 

 Gram's method. 



Jt'eaction. Kesidual product always acid. 



Copious evolution of carbonic acid during the fermentation. 



Among various bacteria at present noted as causing plant diseases, 

 that described by Kramer as attacking the potato (Nassfaule) approaches 

 most nearly to the one which is the subject of this paper. Kramer's 



