102 THE JOURNAL OF BOTANY 
specimens from Chingford, which he examined, were from trees 
of this species. Further, Mr. Walter Fox writes me that the tree 
at Dagenham from which he collected the specimens mentioned 
above was S. fragilis, and that the galled trees at Hornchurch 
were in part S. | aaa and in part its so-called varieties britannica 
and russellian 
other willows. Prof. Nalepa refers * to its appearance on S. alba 
and S. babylonica, as well as on 8. ragtlis. a Hugh Boyd 
Watt says} that at Hampstead he ned observed it on all these, 
and also on S. vitellina.t Mr. Chittenden belive that the 
epegens of the gall submitted to him in 1906 were on S. alba. 
be seen. One thin ng I can aso howev ver, oe some confidence 
rop; and 
that » had it occurred thereon, I diana a observed the fact. 
that it has not yet invaded the district in question. At the same 
wieraet 7 appears, must have a weakening isd generally- 
year, many of its smaller twigs being already dead. It is to be 
crop, will prove to be immune from the gall: otherwise a serious 
economic problem may arise. It is fortunate that S. fragilis, the 
species which seems to be most affected by the gall, is a tree o 
almost no economic value. 
nites The m ssintiotive of cloth was, at that time, largely 
carried on in that district ; and if has been surmised that the 
Marble Gall may have been saledinaed there, either accidentally 
or perhaps experimentally, by someone who hoped to be able to 
utilize it for dyeing purposes, in place of the somewhat-similar 
* Op. et loc. ci t Op. et loc. cit. 
{ On all trees of Salix babylonica growing on Hampstead Heath, the brooms 
assume (as Mr. Watt has pointed out to i m8 unusually large but very thin 
and straggly form, which I have not seen elsewhere. 
