1899-1900.] Dr R. Stewart MacDougall on Genus Pissodes. 353 
wood first of all transversely, and then in the longitudinal direction. 
All behind it was sawdust, and the grub itself was lying in a bed 
protected by the outer layers of overhead wood. In such a posi- 
tion the larva might easily have attained its full development up 
to the imago stage, in spite of the tree having been stripped of its 
bark. 
Experiments. 
In the winter of 1897-98 I obtained some sections of Scots fir 
from Aberdeenshire, and on determining that these were infested 
with the larvae of P. jpmi, I placed them in a sack in one of the 
hot-houses at the Royal Botanic Garden. 
In the beginning of March 1898 the adult beetles began to come 
away, and continued to issue until 20th May. 
With this material I carried out some experiments in order to 
compare this, the largest of our British Pissodes, with the other 
two as regards generation, length of life, and continuance of egg- 
laying. 
Pine 1. 
On 2nd June 1898 a healthy and vigorous growing 6 -feet 
Scots pine was uprooted, and replanted in a large tub. The whole 
was in the usual way surrounded with a muslin sack, and on 
account of the size of the pine placed (in order to avoid accidents) 
in a little outhouse at the Royal Botanic Garden. The door of 
this outhouse stood constantly open, and the weather conditions 
were the same as if the pine had stood exposed save that it 
received a certain shelter from the wind and rain. The pine was 
watered at intervals. 
Eighteen Pissodes pini were introduced, and remained on the pine 
until 29th July. The pine was soon studded all over with drops of 
resin (which ultimately solidified so that the branches were covered 
with little whitish balls), which had oozed out from the punctures 
made by the feeding beetles. 
In the month of August, when examining the pine here and there 
on the stem I noticed the bark swollen, and on such places being 
tested with the finger they ‘gave.’ Dissection at such places 
showed that the swelling indicated the path of the feeding larva. 
VOL. XXIII. 
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