.^84 Transactions of the Canadian Institute. [vol. ix 



Fig. 57. Contents of the stomach of the preceding inquiline. The black 

 masses are parts of cell walls, while the lighter roundish particles 

 are crystals. X300. 



Fig. 58. Holcaspis bassetti Gillette on the stem of Q. macrocarpa Michx. 

 Section through the nutritive zone of a nearly full grown speci- 

 men. The nutritive zone is shov/n to consist of elongated cells 

 next the larval chamber and elliptical further out. The dark 

 zone is a crystal layer that bounds the nutritive zone on the 

 outside. A cambium is differentiated between the nutritive 

 and the parenchyma layers but it is not well shown in the figure. 



X60. 



Fig. 59. Andriciis singularis Bassett on the leaf of Quercus rubra L. 

 Section through the nutritive and protective zones, showing 

 empty cells throughout the nutritive layer and the wrinkling 

 of the radial walls of its cells in general. X 100. 



Fig. 60. Aylax glechomcB Linne on the leaf of Nepeta hederacea (L.) 

 Trevisan. Section through the nutritive and protective zones, 

 showing the unbroken lining of the gall cavity and the row of 

 empty cells that borders the larval chambers. X80. 



Plate X. 



Fig. 61. Philonix nigra Gillette. Longitudinal section of the larva, 

 showing the external opening of the alimentary canal. X15. 



Fig. 62. Amphibolips confluens Harris. Longitudinal section of the 

 larva, showing the completeness of the digestive tract. X15. 



Fig. 63. Rhodites lenticularis Bassett on the leaf of Rosa blanda Ait. 

 Section through the larval chamber, showing the nutritive 

 layer lining it. Bordering this tissue on the outside is the cam- 

 bium zone from which practically the entire gall is originated. 

 The dark band shown plainly at the right of the figure is the 

 protective sheath. X20. 



Fig. 64. Philonix erinacei Beut. on the leaf of Q. alba L. Section in 

 which the four typical zones of a cynipid gall are shown, namely 

 nutritive, protective, parenchyma or tannin, and epidermal. 

 The sclerification can be seen to have passed out into the par- 

 enchyma zone. X25. 



Fig. 65. Holcaspis globulus Fitch on the stem of Q. alba L. Section 

 through adjoining larval chambers of a producer and an in- 

 quiline, a complete section of the latter is shown. The nu- 

 tritive tissue that supplies the inquiline with nourishment can 



