2 BORTHWICK—ON WITCHES’-BROOM. 
although its tissues were still alive. Plate V., fig. d, illustrates 
this—the “broom” is visible in the lower right-hand corner. 
The branches of the “broom” of this Pyrws are much thicker 
and more succulent than the normal ones of the plant ; they are 
also of a light yellow-brown colour and covered with a dense 
felty pubescence contrasting markedly with the thinner dark 
blackish-brown glabrous normal shoots. 
Another interesting abnormality in the “ broom” is the entire 
absence of spines, which are everywhere well developed on the 
normal shoots of the plant. 
As yet no fructifications of a fungus have been detected, but 
microscopic examination shows abundant mycelium in the 
tissues. 
The “broom” will be kept under observation, and the 
subsequent history of its vegetative activity, together with any 
microscopic details which may be of interest, will be recorded in 
a subsequent paper. 
Since the above was written Dr. Solereder has published in 
the “ Naturwissenschaftliche Zeitschrift” for January, 1905, 4 
list of species of trees upon which witches’-broom has been 
observed. To his list Pyrus japonica is an addition, as are also 
the following species, about which I shall say something in a 
subsequent note :—4sculus Hippocastanum, Myrsine africana, 
Quercus Cerris, Ribes alpinum, Ulmus montana. 
Explanation of the F aes 
in Plates IV. and V. 
FIG. a.—Witches’-broom of Pyrus japonica. Both abnormal and normal 
twigs are leafless. From a photograph taken in November 1902. 
1G. &.-—Witches’-broom of Pyrus japonica. “The abnormal twigs are 
still producing young leaves. The normal shoots are almost leafless. From 
a photograph taken in October 1902. 
Fic. ¢.—Witches’-broom of Pyrus japonica. The abnormal twigs show 
no signs of bud-activity. The normal shoots bear numerous young leaves 
and flower-buds. From a photograph taken in February 1903. | 
Fic. d—Witches’-broom of Pyrus japonica. More of the normal twigs 
are shown with young leaves and flowers. The abnormal twigs at the lower 
right corner are leafless. From a photograph taken in February 1993- 
