NOTES ON A DISEASED ACACIA. 
169 
XXVI.— Notes on a Diseased Acacia (Robinia p>seudo-acacia). 
By W. Wilson Saunders, F.R.S. (Read at meeting of 
Scientific Committee, 11th March, 1879h 
When at Torquay, a short time since, my attention was called 
hy my friend E. Vivian, Esq., of that place, to a very remarkable 
diseased trunk and branches of an Acacia (Robinia pseudo- 
acacia), which he had planted in his grounds about the year 
1842, on the north side of a wall 8 feet high, in clayey loam, with 
a subsoil of shale. The tree was cut down in 1870, on account 
of the disease stopping its growth and rendering it unsightly. 
I carefully examined the remains of this tree, and was furnished 
by Mr. Vivian, who is an excellent draughtsman, with a sketch 
of the trunk, and I was allowed to take branches of the tree for 
more rigid examination. I beg now to offer to the Scientific 
Committee of the Royal Horticultural Society carefully executed 
drawings of this diseased Acacia, with sections of the stem and 
branches, which will show the character of the disease, and to 
describe at the same time its peculiar features. So far as I was 
enabled to see the nature of the disease on the stem and 
branches preserved by Mr. Vivian, it appeared as a very regular 
eruptive growth of numerous more or less rounded nodulous 
excrescences, commencing at the very base of the main stem and 
extending to the very extremity of the branches. These 
excrescences were very unequal in size, very variable in outline, 
and very rough and nodulous. They often touched each other, 
and in places formed elongated somewhat transversely ribbed 
masses. Some of the more developed excrescences on the 
main stem protruded nearly two inches from the general line of 
the stem, while others on the branches were like large rough 
warts, with an elevation of only a quarter of an inch. 
Referring now to the Drawings which accompany this, No. 1 
shows a horizontal section of the main stem near the base, 
opening up two of the excrescences and showing others in profile. 
Here it will be perceived that the bark is thick, very rough 
externally except where it covers the excrescences, and there it is 
much reduced in thickness, being scarcely one-eighth of an inch 
through. The sap wood is well marked and runs into the 
