10 TRANSACTIONS OF THE [Sess. lxxvi. 



advantages as regards rate of growth, and is less exacting 

 as regards soil and climate. 



" Secondly, the introduction of an alien species is desirable 

 if it is capable of resisting indigenous diseases, but great 

 care must be exercised so as not to introduce a new disease 

 along with an alien species. An exotic parasitic fungus if 

 introduced may become rampant on indigenous species, and, 

 vice versa, an indigenous parasitic fungus is equalty liable 

 to attack an exotic host. . . . 



" It is therefore quite possible that exotic trees from 

 virgin forests, when introduced into a new country and 

 grown under artificial conditions, may readily become a 

 prey to parasitic fungi, although hitherto in their native 

 habitat they may have been entirely free from disease of 

 any kind." 



We are told that in its native habitat the occidental larch 

 is not attacked hy Peziza WUUcom/mii, and here was an 

 example of an exotic species becoming the prey of an 

 indigenous fungus, or, I should rather say, of a fungus 

 previously introduced from the Continent with the Euro- 

 pean larch. This country was in other words the common 

 meeting-ground of an American host plant and a fungus 

 disease from the Continent. 



As I had already learned from my former teachers in 

 Munich, Professor R. Hartig and von Tubeuf, that such 

 dangers existed, I was glad to be able to add this example 

 as a warning in this country. How little such warnings 

 are sometimes heeded here and elsewhere the following 

 note by Professor von Tubeuf in his Journal, entitled 

 " Naturwissenschaftliche Zeitschrift fiir Forst- und Land- 

 wirtschaft," will show. He says : " In an article published 

 in the Year-Book of the German Dendrological Society for 

 the year 1904, p. 156, I drew attention to the danger and 

 frequency of the spread of plant parasites by commerce, 

 not only within a country, but from one country to another, 

 and even to distant parts of the world. I also cited several 

 instances of such occurrences. The transmission of the rust 

 disease of the Weymouth pine within Germany by young 

 infected plants was a typical example. 



" The news which now comes from America is still more 

 interesting and significant. This dangerous disease of the 



