184 Report’ oF DEPARTMENT OF BACTERIOLOGY OF THE 
and radish roots and cabbage petioles have shown practically 
Similar conditions. The rate of softening of sections of these 
tissues in solutions of the enzym-containing precipitate and in 
living cultures has proved to be more rapid in the turnip, 
radish and cabbage tissues than in those of the carrot. In the 
latter the action was faster on the core than on the cortex 
tissues. It was more rapid in the young potato than in the 
mature tuber. On the beet root no action whatever occurred. 
In order to secure data for the above conclusions careful 
trials were made on two occasions with a 5% solution of an 
alcoholic precipitate containing a not very active enzym, This 
weaker enzym, acting more slowly, permitted more satisfac- 
tory differentiation between the rate of softening of tissue 
of similar susceptibilty. The trials were made about July, 
using vegetables fresh from the garden except for the potatoes 
of Series I. The details are as follows: 
Series I. Using thick razor sections of (1) old potato, core; 
(2) young carrot, a. core, b. cortex; (8) young radish, core; 
(4) young turnip, core; (5) cross sections of young cabbage 
petiole. The interval before complete disintegration was: 
turnip, forty minutes; radish and cabbage, about forty-five 
minutes; carrot core, eighty minutes; carrot cortex, ninety min- 
utes; potato, one hundred minutes. 
Series II. Using similar solutions and vevretable sections, 
except that sections from a young potato tuber fresh from the 
garden were substituted for the old potato (1), and the fol- 
lowing were added : (6) cotyledon of pea, approaching ma- 
turity; (7) root of beet. The intervals before complete dis- 
integration were turnip, radish, cabbage (about alike), thirty- 
five minutes; young potato, carrot core (about alike), eighty 
minutes; carrot cortex, pea (about alike), one hundred min- 
utes; beet, limp but no signs of disintegration even after 
twenty-four hours’ immersion. ; 
These observations as to the rate of action of the enzym on 
plant tissues clearly accord with the results from inoculations 
into the corresponding vegetables made in our earlier studies 
(1900: 307) and indicate, what we would expect, that aside 
from moisture relations the relative susceptibility or resist- 
‘ance of the host plants to infection depends largely, if not 
wholly, upon the composition of the middle lamellae. 
