April, 1904.] Galls and Insects Producing Them. 117 



3. GALLS OF LEPIDOPTERA. 



I gathered a number of L,epidopterous galls on Rudbecki& 

 laciniata L,. which I was unable to determine. These galls occur 

 on both leaf and flower and are very large and fleshy. In fact 

 they were so fleshy and juicy that it was very difficult to secure 

 sections. The parenchyma cells were very large, and small fibro- 

 vascular bundles were numerous. The larval chambers were 

 numerous and each contained a single larva or pupa. In my 

 specimens the larvae were far advanced, many of them in the pupa 

 stage, but the cells next to the chambers were very rich in food 

 supply. 



Part VII. Root Galls. 



Amphibolips radicola Ashm. (Figs. 76a, b). — on Quercus alba 

 Iv. was the only root gall that I collected. The galls were borne 

 just under the surface of the ground at about the point of transi- 

 tion from stem to root. They were produced in great numbers 

 and so closely packed together as to assume the shape of figs. 

 Those nearest the surface of the ground and therefore slightly 

 expo.sed to the light were of a rich, red color, while those deeper 

 in the ground were almost white, slightl}^ tinged with yellow. 

 Kach gall contained from one to five larval chambers. The 

 younger galls showed four zones well defined (Fig. 76a). The 

 inner or nutritive zone was thick and the cells contained abund- 

 ance of protoplasm. The protective zone was thin and the cells 

 fibrous in character rather than sclerenchymatous. The paren- 

 chyma zone was thick and composed of large parenchyma cells. 

 The epidermal zone was relatively thick and the cells firm. As 

 the insects approach maturity the nutritive and protective zones 

 are entirely destroyed (Fig. 76b). The insect eventually makes 

 its escape through an opening in the side of the gall. 



Part VIII. Histology of Galls. 



Man}' of the histological characters of galls have been referred 

 to in the preceding parts. This part has been introduced at this 

 time for the purpose of adding a few additional facts which were 

 not clear at the time of the writing of the preceding parts. 



A. Internal Stttictures. 



I. GALLS OF ACARINA. 



These galls have been sufficientl}' discussed and need very little 

 attention at this time. In general these galls may be thrown 

 into three groups : (i) Those galls in which there is very little 

 distortion, but a modification of the epidermis, as in the case of 

 the Phytoptus on the beech ; (2) Convolutions of the parts as in 

 the case of P. ulmi (Fig. 8), P. abnormis (Figs. 9, 44), P. quad- 



