2 74 The Ohio Naturalist. [Vol. II, No. 7, 



a mere enlargement of the tip of the stem, and containing one or 

 more larval chambers. Examination of section under a compound 

 microscope, however, reveals a condition similar to that described 

 for C. solidaginis and C. s.-strobiloides. Each larval chamber is 

 in reality the apex of a bud. The 3'oung leaves of the bud are 

 closely applied to each other and their structure unaffected b}^ the 

 insect. As the gall developes the leaves do not unfold but assume 

 a corky texture and in the full)^ mature gall their identity is 

 almost lost. 



It is very evident that the larval chamber occupies a correspond- 

 ing position in each of these galls. The insect prevents the 

 elongation of the stem, thus causing the leaves of the apical 

 bud to be bunched and reduced in size. The fact that the leaves 

 of the Solidago reach the greatest development and those of 

 the Quercus the least development is probably due to the char- 

 acter of the plants. Of these three plants the growth of the 

 Solidago is the most rapid while that of the Quercus is the slow- 

 est. In Solidago the rapid growth may be sufficient to overcome 

 the injury and cause the bunch of leaves ; in the Salix where the 

 growth is not so rapid the leaves are smaller and more compact ; 

 in the Quercus where the growth is slowest the bud never opens 

 but becomes corky and the leaves gradually lose their identity. 



This work was pursued during the year i go 1-2 in the Zoolog- 

 ical Laboratory of the Ohio State University under the direction 

 of Professor Herbert Osborn to whom I am indebted for many 

 valuable suggestions. 



LITERATURE. 



Only those references which were especially useful in preparing 

 this paper are cited. 



1. Adler, Hermann, M. D., " Ueber den Generations — w^ech- 

 sel der Eichen Gallwespen" Zeitschrift fur wissenschaftliche 



Zoologie. Bd. ^,s- Leipzig "Alternating Generations, a 



Study of Oak Gafls and Gall Flies," translated by C. R. Stratton. 

 Clarendon Press, Oxford. 



2. Ashmead, W. H. "A Bibliographical and Synon3nnical 

 Catalogue of the North American Cynipidae with descriptions of 

 new species." Transactions American Ent. Soc. Vol. XII, pp. 

 291-304. 



3. Ashmead, W. H. " Synopsis of the North American Sub- 

 families and Genera of Cynipidae." Trans. Amer. Ent. Soc. Vol. 

 XIII, pp. 59-64. 



4. Ashmead, W. H. " On the Cynipidous Galls of Florida 

 with descriptions of new species and Synopsis of the described 

 species of North America." Trans. Amer. Ent. vSoc. Vol. XIV, 

 pp. 125-158. 



5. Bassett, H. F. "Description of several supposed new 

 species of Cynips, with remarks on the formation of certain Galls." 

 Proc. Ent. Soe. of Phil. Vol. II. No. 3, pp. 323-333- 



