able (() iiiuko out the individual liUle spols wliicli ij^o to make 

 up one of lliese coinnion masses. The Avinter staj^^e of tliis dis- 

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

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

 except that, in tlie sumniei' spore stage they are extruded in the 

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

 the 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 two A'ears old, according to the records which were kei)t. 

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

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

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

 Sometimes this bark breaks awa}^ 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 A\iien the disease Avas present, rather than a 

 dejiression. Mere at the left we get the normal size of the twig, 

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

 Ave see AAiiere the disease started, and Ave have this considerable 

 SAvelling. This is quite characteristic, under certain conditions, 

 of tAvigs Avhicli are less than a half inch in diameter. It some- 

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

 monly in this type of branch. 



No, 11. In the older trees, Avhere the bark has become deeply 

 fnrroAved, 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 Avhat you 

 might imagine, — and some of the furroAvs. We get the yelloAvisli- 

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

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

 all. 



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

 NoAV Avhen 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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