134 HENRY G. SMITH. 
determine its affinities, and if possible its relationship to 
the later structure of the leaf. 
There seems to be no strict regularity in the time of year 
when the formation of this elastic substance is most pro- 
nounced, and no fixed period appears to be necessary for 
its production. A few years ago, I gathered, early in 
December, some material from the young shoots of A1ngo- 
phora lanceolata at Sandringham, near Sydney. At the 
end of the following October it was plentiful on the young 
growth of both EH. corymbosa and A. lanceolata, at La 
Perouse, near Sydney; two months later, however, none 
of the elastic coating could be detected. The formation 
thus appears to be largely due to climatic conditions, which 
cause the plant to send forth fresh shoots, and thus to give 
the tree new growth. 
In the beginning of March of this year (1908) there was 
quite a marked and vigorous growth in the Hucalypts 
growing around Sydney, evidently due to the rainfall of 
the previous month. At this time the elastic substance on 
the shoots of both E. corymbosa and A. lanceolata was 
most pronounced. By the beginning of June it was difficult 
to find any of it remaining, and it was only evident in 
quantity on very few plants. As this appeared to be a 
very good opportunity to obtain sufficient material to carry 
out the investigation, a large quantity of the fresh shoots 
and very young leaves of both these plants was collected. 
The trees were growing together on the hills beyond Cook’s 
River, near Sydney. The collection was a somewhat 
tedious process, as it was of little use gathering more than 
the terminal shoot with at most the two extreme very 
young leaves. The shoot at the end of the branchlet, 
before the leaves were unfolded, was entirely covered with 
the elastic coating. It was necessary to use considerable 
force to pull the shoot apart, as the elastic substance occurs 
