DISEASES OF TAXODIUM AXD LIBOCEDRUS. 



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 t while those of many fungi are active 

 in distinctly acid media although growth is more vigorous in 

 neutral solutions. J 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. c.) pointed 



* Marshall-Ward, H. On a lily disease. (Ann. Bot. 2 : 319. 1889.) 

 f Fermi, Claudio, Weitere Untersuchungen tiber die typischen En- 

 zyme der Micro-organismen. (Cent, f . Bact. u. Parasitenkunde 10 : 404. 

 1891.) 



% Hansen, A. Die Verflussigung der Gelatine durch Schimmelpilze. 

 (Flora n. s. 47:88. 1889.) 



Green, J. B. 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.) 



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