XII.] PINE-BLISTER. 261 



Sections through the czcidia and spermogonia on 

 the cortex present structures so similar, except in 

 minute details which could only be explained by 

 lengthy descriptions and many illustrations, that I 

 shall not dwell upon them ; simply reminding the 

 reader that the resemblances are so striking that 

 systematic mycologists have long referred them to a 

 mere variety of the same fungus. 



Now as to the kind and amount of damage caused 

 by the ravages of these two forms of fungus. 



In the leaves, the mycelium is found running 

 between the cells (Fig. 39, //), and absorbing or 

 destroying their contents : since the leaves do not 

 fall the first season, and the mycelium remains living 

 in their tissues well into the second year, it is 

 generally accepted that it does little harm. At the 

 same time, it is evident that, if very many leaves are 

 being thus taxed by the fungus, they cannot be 

 supplying the tree with food materials in such 

 quantities as if the leaves were intact. However, 

 the fungus is remarkable in this respect that it lives 

 and grows for a year or two in the leaves, and does 

 not (as so many of its allies do) kill them after a few 

 weeks. It js__also stated that only young pines are 

 badly attacked by this form : it is rare to find acidia 

 on trees more than twenty years or so old. 



