364 BOTANICAL GAZETTE [May 
another derived type (3), although this may be interpreted as 
having an independent origin. 
CoLropTeRA (pl. XXI).—Despite the vast size of this order and 
the intimate food relation many of its members hold with living 
plants, there has been but a slight development of the gall-making 
habit. They may all be included under the type shown (1), 
which is a simple cortical kataplasma. 
LeprpopTera (pl. XXI).—These are all stem galls of simple 
constitution. A number of the insect families are involved. The 
hyperplasia commonly affects all tissues about equally, so that 
there is merely a local enlargement of the stem (1), with a cavity 
occupying the pith region. The differentiation is uniformly 
weaker than in the normal stem; it is a low kataplasma. 
The Lepidoptera and the Coleoptera are commonly given a 
higher position than the Hemiptera which follow: Since they 
show no complex gall phylogenies, they are placed out of position 
near a few other unimportant groups. 
PsyLLipak (Hemiptera) (pl. XX1I).—Three original lines of attack 
on the plant appear to have been made in this group, two of which 
(x and 1o) end blindly in inconsequential kataplasmas. The 
third primitive form, simple leaf fold (2), is probably ancestral to 
the simple leaf edge-roll (9) and a diverticulum kataplasma (3), 
from which type certain highly specialized prosoplasmas are 
believed to have sprung. The psyllid prosoplasmas, which are 
only known from America where they occur on the buds and leaves 
of the hackberry (Celtis), constitute in themselves an excellent 
evolutionary series, the main outlines of which are indicated in the 
diagram (4-8). The presence in all of them of specific scleren- 
chyma layers, together with other highly defined tissue form 
characters, makes them striking examples of prosoplasmas. No 
related kataplasmas, that is, on the same host, are now existent. 
APHIDIDAE (Hemiptera) (pl. XXI).—All of the galls of this group 
probably have sprung from the simple leaf fold (x), which, since 
the insects are commonly numerous locally, appears in the highly 
variable compound form or the crumpled, wrinkled, or otherwise 
distorted blade. The number of these primitive aphid leaf con- 
volutions is legion. From these have sprung the indefinite edge- 
