April, 1904 .] Galls and Insects Producing Them. ri 9 
4. GALLS OF CECIDOilYIA. 
These galls have been described in Part I (Figs. 22, 23, 24), 
in Part V (Figs. 61, 62, 63), in Part VI (Figs. 73, 74, 75), and 
in the Appendix (Figs. 114-119). In these galls the two zones 
are usually fairly well defined, but the galls of this genus are so 
different in character that it is difficult to give a definite descrip- 
tion. The time for the formation of the tannin is variable, but 
it is usually produced late and in great abundance. 
5. GALLS OF THE CYNIPIDAE. 
All these galls are ver}' similar. The majority show the four 
zones and in most cases the.se zones are well defined. The outer 
zone is the epidermal which will be described later (Figs. 84-91). 
The second is the parenchyma zone ; the third is the protective 
zone made up largely of sclereiich3una, and the fourth or inner- 
most is the nutritive zone. In many ca.ses the second and third 
zones become partiall}' or entirely separated. This separation, 
however, is not between the second and third zones as previousl}^ 
stated bj' me in Parts I and V, and b}’ Fockeu, but rather a sep- 
aration of the tissues of the second or parenchyma zone, the 
greater part of this zone clinging to the epidermal zone and a few 
cells remaining attached to the protective zone. 
Diastrophus siminis Bassett (Figs. 66-69) has been described 
in Part The four zones are distinct and each shows the char- 
acter previousl}' referred to. 
Diastrophus nebulosus O. S., described in the Appendix (Figs. 
129a, b), is a stem gall in which the zones are well defined, the 
protective zone being especially’ well developed. Each zone shows 
the characters previously referred to. 
In Amphibolips confluentus Harris (Figs. 121a, b, c) the first 
and second zones are well developed, but the distinction between 
the third and fourth is not so pronounced. 
In Amphibolips inanis O. S. (Fig. 28) the four zones are well 
defined. In the young gall (Fig. 79) the cells of the nutritive 
zones are very* rich in protoplasm and there is very’ little or no 
distinction between the nutritive and the protective zone, but as 
the galls approach maturity’ the cells of the protective zone 
become very thick and are soon converted into sclerenchyma 
( Fig. 80). 
In Callirhy’tis papillatus O. S. we have the four zones well 
defined (Fig. 30). As the gall approaches maturity the cells of 
the nutritive zone lose their protoplasmic contents and become 
very much shriveled, the protective zone is made up usually^ of 
only two or three layers of cells. Next to the protective zone are 
two or three layers of cells which are in reality’ a part of the 
parenchy’ina zone. The large intercellular spaces formed in this 
