300 
The Gatiker of the Larch. 
more sevious where the trees are grown for tiraber, as the canker 
greatly distorts the trunk, if it does not entirely kill the 
tree. 
In the course of last summer's visit of inspection to the 
famous pastures of England the Consulting Botanist found 
cases of canker in larch plantations all over England and Wales. 
Indeed, the disease is unfortunately too prevalent throughout 
Britain, and seriously endangers the profitable growth of one of 
our most valuable timber trees. 
It is proposed in this paper to give an account of the cause 
of the canker and to record the results of a somewhat lengthy 
investigation of the subject, based on numerous specimens kindly 
placed at my disposal by the Eai'l of Ducie and Mr. Faunce de 
Laune, as well as to record observations made on living trees in 
various parts of Britain. 
The existence of canker in the larch has been known in 
England for a considerable time, but it is difficult to determine 
the exact period when the canker was first observed, as half a 
century ago arboriculturists attributed the internal rot of larches 
to the same cause as canker. In 1860 Mr. Charles Macintosh, 
the well-known landscape gardener, published a special work on 
the larch disease in Great Britain. This contains a careful 
review of all the literature of the subject up to that time, as 
well as a record of the opinions of scientific and practical men 
on the origin and nature of the disease. The author believed the 
injuries to be due to errors or faults of cultivation. Bad draining, 
planting on unsuitable soils, and using inferior seedlings were 
considered to be the chief agents in causing the disease. Even 
at that time it was feared that the canker would be fatal to larch- 
growing in Great Britain. 
In 1882 Mr. C. Y. Michi?, forester to the Earl of Seafield 
at Cullen House, published his practical work on " The Larch." 
He devotes a chapter to its diseases and in a few sentences^ dis- 
poses of the canker. It is evidently the result, he holds, of such 
causes as confinement, superabundance of moisture, cold wet 
seasons, spring frosts, or, indeed, anything that injures the 
outer coating of the bark. This disease, he says, is most in- 
veterate on wet, cold soils, such as the border-lands of Scotland 
and the north of England. 
The Ihiglish Arboi'icult ural Society ottered a prize for an 
essay on the canker in the larch, which was adjudicated to 
Mr. ■\Villiam Clark in April 1886. I\fr. Clark considers that tlie 
disease is generally found on undrained, I'etentive soils of bog or 
clay, and that the trees attacked are often found to be unsound 
or widely rotten at the core. He regards the variable climate 
