282 AN INQUIRY INTO THE CAUSES OF THE DEATH OF 



of the living branch and gradually killed and discoloured the 

 wood on that side. The latter seems to be the true explanation. 

 When the specimen was taken the disease was spreading across 

 the twig, and would in time have cut off all water supply from 

 the small branch. The equally forked branch referred to above 

 points to the same conclusion. 



It is evident that for perfect confirmation of this view, some 

 successful inoculation experiments are all that is required. So 

 far it has not been possible to iind a perfectly healthy district, 

 so that should the inoculation prove successful the evidence 

 would for that reason be materially weakened. My test cases 

 have produced no marked results as yet, but this no doubt is 

 owing to difficulties that have still to be overcome. In the 

 ordinary course of events it is the top branches that first develop 

 the disease and I have been able to inoculate only the lower 

 branches in districts where the disease is prevalent. 



The following extracts support my view : — • 



Diseases of Plants induced by Ciyptogamic Parasites. By Dr. Karl PYeiherr 

 von Tubeuf. Eng., Ed. by W. G. Smith, 1897, P 224. 



" I'dlsti oxystoma causes disease and death of branches of .\lnus viridis in 

 the Alps. The symptoms are withering up of single branches of an otherwise 

 green bush. In the branch attacked a mycelium is developed in the vessels of 

 the wood whereby the water is stopped and the bark dries up. Black lens- 

 shaped stromata arise under the epidermis of the twig and rupture it. 

 Perithecia are produced under the stroma of the bark, and communicate with 

 the e.xterior by means of long projecting necks. The asci contain eight 

 unicellular spores of a slightly bent rod-like shape. Maturity is reached on 

 the dry dead twigs." 



Diseases of Trees. By Professor R. Hartig. English Ed. 1S94. Page 151. 



" In Alpine districts a disease is very prevalent on Alniis viridis 

 Numerous stems and branches contract the disease and die. It is chiefiy in 

 August that the leafy branches become infected. The withering of the 

 cortex attracts attention to the presence of the disease, and directly after- 

 wards small black tubercules appear on the dead tissue. The stage of the 

 development of the pustules depends upon the length of time since the branch 

 died. Thus, although the presence of the fungus may be detected on 

 branches that are still living, it is met with in its highest form only on such 

 as are perfectly dead. The progress of the disease down the stem is indicated 

 by a sharp line between the diseased wood which is brown and that which is 

 sound. As the disease advances other lateral branches become affected. An 

 e.xceedingly tough and vigorous mycelium is easily discernabie in the 

 moribund wood especially in the vessels. 



