364 



tion of a gall is (1) the excitation of growth and cell division, (2) the 

 failure of the cells of the affected part to differentiate into the character- 

 istic tissues of that part, and (3) the differentiation into characteristic 

 tissues of the gall. We also recognize certain similar lines of develop- 

 ment in what we now consider well-defined genera. The explanation of 

 the similarities and differences in these lines of development will depend 

 largely upon future work in both taxonomy and histology. 



It is the purpose of this paper to call attention to certain points above 

 referred to in connection with the genus Ampliibolips. The taxonomy of 

 the insects of this genera have been very thoroughly studied and carefully 

 described and arranged by Mr. Win. Beutenmuller. 3 The writer has also 

 studied the histology of several of the galls. 



The genus Amphibolies belongs to the family Cynipidese, is quite dis- 

 tinct, and stands high in the line of development. As previously stated, 

 the galls originate as a result of stimulation of meristomatic tissue, re- 

 sulting in growth and cell division. This is followed by a differentiation 

 of this mass of cells into the tissues characteristic of the galls. In the 

 cynipidous galls we have the four distinct tissue zones which have been 

 referred to by many writers, viz: (1) the epidermal zone, or outside 

 layer of cells, (2) the parenchyma zone, which may be quite thick, either 

 dense or loose, and in which may be found fibrous tissue radiating from 

 the center of the gall. (3) the protective zone, composed of sclerenchyma 

 tissue and varying in thickness in different species of galls, (4) the nutri- 

 tive zone of parenchyma cells, rich in protoplasm and immediately sur- 

 rounding the larval chamber. The galls belonging to this genus have the 

 four well-defined zones, but with variation in the parenchyma and pro- 

 tective zones by which they may be subdivided into the following groups : 



Group A. 



Amphibolips confluens, Harris. 



" caroliniensis, Bassett. 



longicornis, " 



acuminata, Ashmead. 



3 The Species of Amphibolips and their Galls. Bulletin of the American Mu- 

 seum of Natural History, Vol. XXVI, Art. VI, pp. 47-66. 1909, 



