365 
1916-17.] The Family Chermesidae. 
less than that of potassium cyanide, as the former liberates about 30 per 
cent, more hydrocyanic acid gas than does the latter. 
Nicotine. — The gas was produced by vaporising a liquid compound 
containing about 39 per cent, of nicotine in a vaporiser. 
Carbon bisulphide. — This gas was produced by allowing the liquid to 
vaporise. 
PART II.— BIOLOGICAL. 
The biological experiments were carried out in a small wood at 
Drumshoreland, West Lothian. In this wood were mixed Picea excelsa 
(Lk.), P. alba (Lk.), P. nigra (Lk.), Larix europoea (D.C.), L. leptolepis 
(Gordon), Pinus sylvestris (L.), Pseudotsuga douglasii (Carr.), and hard- 
woods. The age of the trees varied from five to fifty years. 
(1) Genus Chernies s. str. 
The author has found the species of this genus on the following hosts 
in Scotland : — 
Primary or Picea Host: Picea excelsa (Link.), P. alba (Link.), P. orien- 
tals (Link, and Carr.), P. morinda (Link.), P. sitkensis (Trautr. 
and Meyer). 
Intermediate or non-Picea Host : Larix europoea (D.C.), L. leptolepis 
(Gordon), L. occidentalis (Nutt.). 
Generation I. Fundatrix. — Fundatrices were found hatching both 
from fertilised eggs and eggs laid by gallicolae during August and Sept- 
ember. These larvae were active, and wandered over the branches before 
settling ; this activity aided in the dispersion of the larvae where such had 
hatched from eggs laid by gallicolae. The larvae from the different sources 
differed as follows : — 
A. Those hatching from fertilised eggs were green. 
B. Those hatching from eggs laid by gallicolae were yellow. 
In one or two days after hatching the larvae settled down in a crevice 
at the bases of fairly strong buds, but seldom the buds of leading shoots. 
Each inserted its suctorial mouth-apparatus, secreted short curly “ wool,” 
and hibernated. Frequently many larvae were present around a bud, and 
then they spread on to the bud and down the stem ; only one or two such 
larvae completed their development. Feeding began around the middle 
of March. The first moult took place during the first week in April. The 
suctorial apparatus seemed to be withdrawn before moulting, as the cast 
skin was seldom anchored to the bud. The newly moulted larva was soft 
