130 THE ENTOMOLOGIST. 



discontinued growth through parasitism, to which it is 

 unnecessary to refer further than to explain that fig. 2 shows 

 the normal section of the perfectly -formed gall; and fig. 3 

 the same, inhabited by Synergi. Within this woody cupule 

 several small oval, hard, but thin-walled chambers are 

 frequently to be found. They are irregularly distributed ; 

 sometimes three or four are arranged side by side on the 

 exterior of the woody growth; at others they are quite 

 without any method, and I have found them as far down the 

 twig, to which the gall is attached, as shown at a in fig. 4. 

 It is these chambers that are the home of Andricus trilinealus. 

 This is the only instance known of what is considered a true 

 gall-maker being dependent on another. With this exception 

 the galls and habits of A. trilineatns accord somewhat with 

 those of its congener, A. noduli. The larva chamber in all 

 single-celled or unilocular galls continues, under natural 

 circumstances, single and hollow ; but when these galls 

 become tenanted, with those cynipideous inquilines of most 

 of the cynipideous galls — the Synergi, they all exhibit in 

 section several secondary chambers, divided by a thin 

 vegetable septum. The study of these occasional growths is 

 certainly necessary for correct views of the physiology of the 

 gall itself. 



Now to return to our moje observable instances. First the 

 production of Cynips Kollari. Its normal structure is a 

 smooth, brown, spherical, woody or parenchymatous gall, 

 containing a small more or less oval larva chamber in the 

 centre (see fig., Entom. vii. 241) : this is moderately hard, 

 owing to the density of structure ; the parenchyma — or 

 what is perhaps more correctly described as merenchyraa, 

 from the openness of the structure — is entire, and radiates 

 from it. Two internal and constant modifications occur. 

 The first is when we find two or three chambers in 

 the parenchyma of the gall (see figs. A and b) : these are 

 generally small, single, and invariably placed very near the 

 base of the gall itself. The outward indications of this is 

 small, as the gall appears perfectly normal, and the central 

 larva chamber not being affected the life of the cynipideous 

 tenant, or its parasite, is not interfered with. These chambers 

 are inhabited by inquilines, mostly, if not exclusively, by 

 Synergus melarwptis or its parasites : their presence is to be 

 discovered by a very minute swelling and slight discoloration 

 (lighter) at the point affected ; the perforature of oviposition 

 is also observable in the rind. The second modification 



