NOTES ON THE ANATOMY OF THE PUNCTATUS GALL 533 
several layers of cork cells, and it is possible that it has resulted from 
the sting of the insect in depositing the egg in the bark, as no other 
causal evidence is shown. Kiister (13, p. 187) states, however, 
that wound-cork does not result from such action but callus tissue 
instead. 
There has been no increase in the formation of wood near the gall 
at this stage if a slight protuberance on the lower lef t hand side of the 
chamber in fig. i be excepted. In fact the production of woody tissue 
has been somewhat inhibited at the base of the chamber. A mass of 
parenchyma has been formed here, the cells of which have thin un- 
lignified walls. Later the walls of these cells thicken and lignify 
resulting in the condition shown in fig. 3. A few short scalariform 
tracheids and other lignified elements are scattered among these 
parenchyma cells, very much disarranged in their positions. 
In the stage of development shown in fig. i, all of the chamber is 
surrounded by bark tissue except the inner side of it. A later stage 
(fig. 2) shows the inner part of a chamber to be embedded in woody 
tissue. The way in which this comes about can be studied to best 
advantage in serial sections cut tangentially through the gall. Usually 
the first woody tissue to appear, in the outermost sections of such a 
vseries, is small irregularly arranged masses, which, in sections a little 
further in, take roughly the form of small fibrovascular bundles (fig. 4). 
In this figure a small portion of the protecting layer is shown on the 
lower side. These pseudo-bundles sometimes join directly one with 
the other, or distinct ra\^-like masses of parenchyma and other cells 
may occur between them. The bundles often extend but part way 
around a chamber, other parts of it being surrounded by irregularly 
arranged masses of wood cells. Longitudinal sections through a cham- 
ber often show these bundles extending parallel with it in the barky 
covering of the gall. They are composed largely of bands of scalari- 
form tracheids. Numerous galls have been examined in this regard 
and the bundles have always been found to be present to a greater or 
less extent. They are confined to the bark and thus form only the 
outer part of the woody covering of the chamber. The inner portion 
of the larval chamber is surrounded by woody tissue formed by the 
cambium. Soon after the gall starts, the cambium ceases its activity 
at the base of the chamber while it is stimulated to greater growth 
along the sides. The first stage of the enclosing process is shown in 
fig. I, where a slight woody projection has formed at the lower left- 
