DISEASES OF TAXODIUM AND LIBOCEDRUS. 63 
variable. Marshall-Ward * finds that in a distinctly alkaline 
liquid the mycelium of Botrytis will no longer grow. The 
enzymes of most bacteria are effective only in alkaline 
or neutral media ft while those of many fungi are active 
in distinctly acid media although growth is more vigorous in 
neutral solutions.t Green § notes ‘‘ the possible significance 
of the inhibitory effects of traces of acid or alkali in the 
solution in which the enzyme is working,’’ and Smith || has 
made similar observations. It is suggested that the humus 
compound may, because of its acidity, bring about condi- 
tions unfavorable to the activity of the enzyme formed in 
the cypress wood. As the humus compound is at first in 
liquid form, it saturates the wood cells for some distance 
around the hole, and thus completely fills the space where 
the mycelium is growing and many of the cells outside of 
this space. This explains why the hyphae as a rule grow 
out from the holes in straight lines without branching much 
in the wood surrounding the holes. 
The enzymes are usually soluble in cold water, and can 
be precipitated from a solution by an excess of alcohol. 
Masses of diseased wood finely divided, as well as masses 
of mycelium, were digested with cold water for 27 hours; 
then to four parts of alcohol one part of the extract 
was added. A gray flocculent precipitate was obtained 
which on drying in a vacuum turned slightly darker. It 
was slightly soluble in water. Sections of Taxodium wood, 
young bean stems, etc., when placed in such a solution 
showed no perceptible change. As Hansen (1. ¢.) pointed 
* Marshall-Ward, H. On a lily disease. (Ann. Bot. 2; 319. 1889.) 
+ Fermi, Claudio, Weitere Untersuchungen itber die typischen En- 
zyme der Micro-organismen. (Cent. f. Bact. u. Parasitenkunde 10 ; 404. 
1891.) 
t Hansen, A. Die Verfltissigung der Gelatine durch Schimmelpilze. 
(Flora n. s. 47:88. 1889.) 
§ Green, J.R. On Vegetable ferments. (Ann. Bot. 7:83. 1893.) 
|| Smith, E. F. Sensitiveness of certain parasites to the acid juices 
of host plants. (Abstract in Bot. Gaz. 27:124. 1899.) 
41 
