754 Forestry Quarterly. 



ing resistance, others susceptibility. Coniophora cerehella, a form 

 closely related to Merulius, behaves similarly toward oak, al- 

 though both produce a destructive decay in conifers and certain 

 other hardwoods. It is very possible that other fungi have been 

 confused with these species in literature. The cause of im-' 

 munity has not been worked out, but the author suggests that 

 it is less physical than chemical, and promises further work on 

 the question. 



C. J. H. 



Havelik, Karl Der Hausschwamm in der Natur. Zeitschrift fiir Forst- 

 u. Jagdwesen. September, 1910. Pp. 573-577- 



Wehmer, C. Resistenz dcs Bichenholzes gegcn Hausschwamm. Bericht 

 deutsche botanische Gesettschaft. 191 1. Pp. 704-708. i fig. 



In an attempt to throw light on the immunity 

 Tannin of oak wood to the attacks of Merulius 



on lachrymans Wehmer takes up the relation 



Merulius of various tannins and their cleavage pro- 



ducts to the growth of this organism. He 

 calls attention to the loose use of the term "tannin" in literature 

 and to the fact that oak-wood tannin is not identical with that 

 of the bark or the galls. Comparable figures on the tannin con- 

 tent of various parts of the tree are not available, but the writer 

 succeeded in getting only 4% of extract from the heart, only 

 part of which consisted of tannin. Since oak-wood tannin is 

 not in the market Wehmer selected gall-tannin and gallic acid 

 for his tests, using malt-agar, malt-gelatine and starch paste, to 

 which were added certain nutrient salts, as media. The tannin 

 or gallic acid was mixed with these in various proportion, the 

 flasks sterilized and then inoculated with the mycelium of the 

 fungus in question. While the various media gave somewhat 

 different results in general, .5 to 1% of either substance plainly 

 inhibited growth, while 1-2% completely stopped it, tannin prov- 

 ing slightly more toxic than gallic acid. In contrast to Merulius 

 it was found that Penicillium grew rather quickly on 5-10% con- 

 centration. Since tannin tends to liquefy and precipitate the 

 media on heating, particularly gelatin, the tests are only approxi- 

 mate. 



Small blocks of oak heartwood were also extracted with hot 

 water for varying periods. This was found to render them suit- 



