I20 TRANSACTIONS OF ROYAL SCOTTISH ARBORICULTURAL SOCIETY. 



the dominant, if not among the pre-dominant. Nevertheless, 

 this type is probably of slower growth than the others, both 

 in height and girth. It does not produce a gross growth of 

 main branches, but forms a fairly dense crown by means of 

 secondary branches and twigs. The foliage has a resemblance 

 to that on the fissure-barked type, and is fairly abundant. 

 While its stem-form is fairly good in a silvicultural sense, its 

 position in regard to the other types is doubtful at the moment. 



While the above are a few of the salient characteristics of 

 the types, this by no means exhausts the list of differences, 

 and the writer believes that there is a field here for botanical 

 and silvicultural research. As the tree is a recent introduction, 

 it is probably too early yet to speak of what has been inherited 

 and what acquired, so that under the circumstances it might 

 add considerably to our knowledge of the species, if we knew 

 definitely if some such types are recognisable in the tree's 

 native habitat. 



Entering the field of speculation, one would be inclined to 

 say that the types enumerated protect their cambium layers 

 from various forms of injury, each by different processes that 

 need not be further discussed here. 



Some species of Aphidae, probably Chermes laricis, has been 

 more or less common on the Japanese larch in recent years, 

 and observations tend to lead to the conclusion that it is most 

 prevalent on the smooth-barked type, as would naturally be 

 expected. The connection between insect injury and the new 

 disease is in the realm of analogy as yet, but if the recently 

 recorded fungus {Phomopsis sp.) proves to be a wound parasite, 

 injury of some sort must be pre-supposed. The side shoots 

 of the branches are subject to attack by the insect Argyresthia 

 laevigatella, with the result that they die back to the point of 

 attack. 



The first observation of what in all probability was this 

 fungus, by the writer, about four years ago, was on a shoot 

 which had been damaged by Argyresthia, and of course the 

 form must have been saprophytic. The immunity of the 

 flake-barked type, up to the present, may prove to be a 

 matter of great silvicultural importance, as, while no specimen 

 of this type showing symptoms of the disease has come under 

 the writer's notice, numerous stems of each of the other two 

 types, badly affected by the disease, have had to be removed. 



