268 BORTHWICK—ABNORMAL BRANCH OF PRUNUS AVIUM. 
He appealed to forest officers to send him twigs from any of 
these brooms which might come under their observation, in 
order that further investigations might be made. 
Professor Solereder! soon after gave an account of a Withes’ 
Broom on Quercus rubra L., although he was unable to deter- 
mine the cause, and in additon to this he took the great trouble 
of going through the literature on Witches’ Brooms, and gives us 
at the end of his article a list of all “Brooms” known to occur 
on woody plants and at the same time references to the more 
important literature concerning them, and so far as known the 
cause ofeach. This list was a most welcome and very important 
addition to the literature on the subject. Since then several 
additions have been made to this list, and no doubt more will 
follow. 
Following upon the request by Tubeuf for information, Franz 
Muth? took up the investigation of broomed pear trees growing 
in the forest above Oppenheim on the right bank of the Rhine. 
He found very evident fungus mycelium in the wood of the 
attacked branches, but*as no fructifications could be got it was 
not possible to determine the species. With his article Muth 
gives photographs of a peculiar and abnormal branch develop- 
ment on a pear tree near Durlach in Baden. The tree bears a 
thickly branched upright bush supported on a branch almost as 
thick as the main stem of the tree. The cause of this abnormal 
branch development is attributed by Muth to a rind disease 
caused apparently by a fungus. Although he does not call this 
a Witches’ Broom, still it evidently belongs to the same category 
of diseases, 
Muth’s observations are interesting in relation to what appears 
to be a similar phenomenon which is shown in the abnormal 
branch growth of the specimen illustrated in Plate lit. This 
tree is, however, Prunus avium, and is growing in the policies of 
an estate in Midlothian. A side branch seems to have been 
attacked and has developed to extraordinary dimensions, form- 
Ing as it were a secondary bole on the tree. On the shoot- 
system belonging to this secondary bole several smaller, but 
*Solereder in Naturwissenschaftliche Zeitschrift fur Land und Forstwirtschaft, 
January 1905, p. 17. 
2 h - . . * a ee rT 
Muth in Naturwissenschaftliche Zeitschrift fur Land und Forstwirtschaft. Uber 
den Birnenhexenbesen, February 1905, p. 64 
