175 



The parasites, under whose influenoe abnorraal tissues 

 are prodixc e'd. are drawn from the plant and animal Icingdorns, 

 (" Phyto»oecidla " - "Zoccecidia") . The higher plants take 

 part here "by me^ns of~"fhe Loranthaceae , while among the lower 

 plants fungi especially come into consideration as Inoitors 

 of gall formation. The animals which produce galls beifenng 

 among the worms and the Arthropoda - the greatest majority 

 by far among the latter. Mites and Insects eapeoially pro- 

 duce the most diverse galls on the most widely different 

 kinds of plants* The iiptera and Hymenoptera play the most 

 prominent role and rmong'the latter belong the gall wnsps 

 (Cynipida) which can produce the most oomplioated of all gall 

 fofmations. Further the Hemiptera should be named, among 

 which are found many gall -producing leaf lice and shield lloe, 

 and final3.y the butterflies and beetles, of which, however, 

 only a small number of representatives are known to produce 

 galls* 



In out histological observations, we can enter only very 

 briefly into the nature of the producers of galls. At times 

 it will be demonstrated that parasites, closely inter-related 

 can produce the most different kinds of heteroplastic tissues , 

 At any rate, fungi galls belong almost entirely among the kat- 

 aplaemas-^, on the ether hand, the galls of the Cynipida belong- 

 predominantly among prosoplasmas, while galls of both kinds 

 are produced in large numbers by Diptera and Zymenoptera, Also, 

 among prosoplasmas thsmselvea, fixed relations between the 

 quality of the abnormal tissues and the systematic position of 

 the producers of the gall are neither very numerous hor strik- 

 ing; thus, for example, the leaf -wasps which produce galls of 

 a simple structure are most closely related to the Cynipida, 

 whose complicated products will fully occupy our attentions. 



Plants capable of producing galls , are found represented 

 in all groups of the plant kingdom, sometimes more abundantly, 

 sometimes less so. Cryptogams, in comparison to phanerogams, 

 must be distinguished as being especially poor in galls and 

 the few which they develop have a simple histology. Among 

 phanerogams, the dicotyledons form the group which has galls 

 most abundantly, the representatives of which are capable of 

 developing kataplasmas and prosoplasmas in equal quantities. 

 The galls on trees and shrubs are universally more varied in 

 form than are those of bushes and herbaceous plants. Quereus 

 and Eucalyptus apparently belong to the plant genera which 

 have most abundant galls. 



Compare for exceptions or disputed cases p. Ell, 



