able 1<> make out the individual little spots which go to make 

 up one of these common masses. The winter stage of this dis- 

 ease produces its spores down in the bark; that is, down beneath 

 (he surface of the bark, and so also does the summer spore stage, 

 except that in the summer spore stage they are extruded in the 

 form of these threads, while the winter spores are not extruded in 

 I lie same way, although they are extruded later. 



No. 12. This view represents a diseased spot on an orchard 

 tree. The diseased spot is less than three years old, but more 

 than t.AVo years old, according to the records which were kept. 

 This shows, at the upper part of the picture, how the bark soon 

 loosens and later falls from the tree and the branches, until 

 finally we have simply the bare trunk or a bare branch left. 

 Sometimes this bark breaks away in less than two years, to much 

 the extent that is shown there. 



No. 13. Here is a small twig of a chestnut. A little while ago 

 I mentioned the fact that, in the smaller twigs, we sometimes 

 had an enlargement when the disease was present, rather than a 

 depression. Here at the left we get the normal size of the twig, 

 and then, running out this way towards the apex of the branch, 

 we see where the disease started, and we have this considerable 

 swelling. This is quite characteristic, under certain conditions, 

 of twigs which are less than a half inch in diameter. It some- 

 times occurs in larger branches, but as a rule we get it quite com- 

 monly in this type of branch. 



No. 14. In the older trees, where the bark has become deeply 

 furrowed, I said that Ave found the diseased pustules almost en- 

 tirely in the cracks or crevices of the bark. This represents the 

 surface, greatly magnified, of course, and beyond what you 

 might imagine, and some of the furrows. We get the yellowish- 

 orange pustules in the crevices there, and in various places, 

 whereas the other parts, the raised places, show no pustules at 

 all. 



No. 15. So much for the disease as it appears on the branches. 

 Now when the disease appears on a branch, or on the trunk of a 

 tree, it starts from the common point and radiates in all direc- 

 tions, forming the more or less circular area of disease. Of 

 course, on the trunk of a tree it goes up the trunk from the com- 



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