GALLS 187 



known to us in galls. The Oaks bear a very large pro- 

 portion of the galls of this family, many of the Oak-galls 

 exhibiting very marked dimorphism, as demonstrated by Dr. 

 Adler's researches. Roses bear several different forms of 

 galls on leaves produced by the species of RJwdites ; Rubus 

 bears galls on stems caused by Diastrophus ; and species of 

 Potentilla have the creeping stems galled by Xestophanes. 

 The genus Aulax includes a good many species, and is not 

 so limited in its host plants. Most of the species cause 

 more or less marked swellings in the inner tissues of stems 

 of plants in widely different orders ; thus Aulax Hieracii, 

 Bouche, has been reared from galls on a number of species 

 of Hieraciuin ; and insects that Dr. Mayr could not dis- 

 tinguish from it have been reared from Linaria vulgaris 

 and Cylisus capitatus ; and Mr. Cameron is disposed to 

 regard the maker of inconspicuous galls in knotty rhizomes 

 of a grass (probably the False Oat-grass) as also this species, 

 though named by himself at first A. graminis, because of the 

 difference of food-plants. Other species of Anlax gall fruits, 

 e.g. achenes of species of Scabious and capsules of Poppies. 



Our information with regard to British gall-makers is 

 more completely recorded for the Hymenoptera than for any 

 other group, thanks to Mr. Cameron's work referred to 

 above. 



Most galls can be preserved in a state suitable for 

 recognition by drying them. The large firm closed galls 

 may be dried in an open place, where they are exposed to 

 a free access of dry air but not to direct sunshine. Better 

 results, if convenience permits, are obtained by keeping them 

 in fine dry sand until the twigs and leaves around them are 

 dry. The various Mantle-galls are best dried in sand, with 

 which they should be filled as well as surrounded. This 

 method gives them the support while drying that is required 

 to prevent shrinkage and distortion. Hair-galls and vir- 

 escent plants may be well preserved in the same way ; but 

 they may also be treated with fair success by the simpler 

 method of drying in botanical paper, or between the leaves 

 of a book. 



Soft fleshy galls that contain much sap, such as Currant- 

 galls of Oaks, galls of Weevils on Turnips, young galls of 



