144 The Ohio Naturalist. [Vol. IV, No. 6, 



insect destroys this partition, travels to the end of the tube which 

 projects beyond the body of the gall, and there makes an opening 

 through either the end or the side of the tube and thus makes its 

 escape. Examination of j'oung specimens would probably show 

 the four zones as well defined as in Diastrophus nebulosus. 



Part IV. Developmknt of Galls. 



Examination of very young specimens of Andricus seminator 

 Harris shows three well defined zones (Figs. 131a, b), the pro- 

 tective zone being undeveloped. The fibro- vascular bundles were 

 ver}^ numerous and distributed just beneath the epidermal zone. 

 I have examined a large number of these galls of various ages 

 and have been unable to find any trace of a protective zone. 

 Tannin develops in the outer cells very early and probably helps 

 to form a protection for the larva. 



PLATES XIII-XV. 



112. Section of gall of Pemphigus vagabundus. 



113. Section of gall of Pemphigus rhois. 

 114a. Diagram of gall of Cecidomyia pellex. 

 114b. Section of gall of Cecidomyia pellex. 



115. Section of gall of Cecidomyia impatientis. 



ii6a. Diagram of the gall of Cecidomyia holotricha. 



ii6b. Section of the gall of Cecidomyia holotricha. 



ii5c. Section of the gall of Cecidomyia holotricha. 



117a. Diagram of the gall of Cecidomyia tubicola. 



117b. Section of the gall of Cecidomyia tubicola. 



117c. Section of the gall of Cecidomyia tubicola. 



118. Diagram of the gall of Cecidomyia viticola. 



119a. Diagram of the gall of Sciara ocellaris. 



119b. Section of normal leaf of Maple 



119c. Section of gall of Sciara ocellaris. 



120. .Section of gall of Rhodites bicolor. 



I2ia. Section of gall of Amphibolips confluentus. (Epidermal and parenchyma zones.) 



i2ib. Section of the gall of Amphibolips confluentus. Nutritive and protective zones. ) 



121c. Section of gall of Amphibolips confluentus. ( Elongated cells in the cavity of the 

 parenchyma zone. ) 



122. Section of gall of Amphibolips piunus. 



123. Section of gall of Amphibolips sculpta. 



124. Section of gall of Andricus petiolicola. 



125. Section of gall of Acraspis erinacei. 

 126a. Diagram of gall of Biorhiza forticornis. 



126b. Section of gall of Biorhiza forticornis. (Nutritive and protective zones.) 



126c. Section of the gall of Biorhiza forticornis. (Section of protective and epidermal 

 zones. ) 



127. Section of the gall of Nematus pomum. 



128. Section of the gall of Holcaspis globulus. 

 129a. Diagram of gall of Diastrophus nebulosus. 

 129b. Section of gall of Diastrophus nebulosus 

 130. Diagram of gall of Andricus cornigerus 



131a. Diagram of cross section of t;all of Andricus seminator. 

 131b. Section of young gall of Andricus seminator. 



