April, 1904,] Galls and Insects Producing Them. 119 



4. GAI.LS OF cecido:myia. 



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 very similar. The majority show the four 

 zones and in most cases these zones are well defined. The outer 

 zone is the epidermal which will be described later (Figs. 84-91). 

 The second is the parench5aiia zone ; the third is the protective 

 zone made up largely of sclerenchyma, and the fourth or inner- 

 most is the nutritive zone. In many cases the second and third 

 zones become partially or entirely separated. This separation, 

 however, is not between the second and third zones as previously 

 stated by me in Parts I and V, and by Fockeu, but rather a sep- 

 aration of the tissues of the second or parenchjana 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 V. 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 especiall}^ 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 ver}" little or no 

 distinction between the nutritive and the protective zone, but as 

 the galls approach maturitj" the cells of the protective zone 

 become very thick and are soon converted into sclerenchyma 

 (Fig. 80). 



In Callirhytis 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 realit)' a part of the 

 parenchyma zone. The large intercellular spaces formed in this 



