24 THE LARCH CANKER 



In addition to this experimental work Hartig added to 

 Willkomm's description of the mycelium in the bark, 

 phloem, and wood of the larch. In the wood it was dis- 

 tinguishable in the medullary rays, the resin ducts, and 

 tracheides. In the sieve tubes he noticed that the hyphae 

 bore short extensions, with or without a few branches. 



He added little to our knowledge of macroscopic features 

 of the disease, with the exception of some observations fln 

 the resin flow from the surface of the bark, but he provided 

 some interesting measurements of the growth of canker in 

 the longitudinal direction of the stem. They were taken 

 from three isolated cankers from different altitudes, and 

 though they were insufficient for a just comparison of the 

 rates of growth at these levels, they nevertheless give some 

 indication of the growth of a canker generally. The cankers 

 were measured at 



1. Steinach (Tyrol), 1,300 m. (4,300 ft.) above sea-level. 



2. Grafrath (near Munich), 700 m. (2,300 ft.) above sea- 

 level. 



3. Brunswick Forest Garden, 170 m. (550 ft.) above sea- 

 level. 



The results were as follows : 



After Steinach. Grafrath. Brunswick, 



years cm. cm., cm. 



1 1-0 1-2 1-0 



2 2-2 3-9 3-3 



3 7-0 6-5 8-1 



4 9-4 9-2 *10-5 

 11-6 13-1 13-0 



6 16-8 17-7 14-7 



7 20-2 20-6 16-0 

 21-8 24-8 16-9 



9 24-6 30-5 19-3 



10 27-0 23-0 



The importance of Hartig's work on tree pathology will 

 be best appreciated when it is observed that reference has 

 been made to contributions by this author under the head 

 of nearly every disease mentioned in this book. The vast 

 field of research covered by Hartig appears 'still more 

 remarkable if we remember that when he started on his 

 work the subject was in an entirely chaotic state, and it is 



