193 



phytopti (oT\ Acer Igegundo . Tiltn etc.) not infreqtiently into 

 groups of hun'are'ds on the snme leaf, 



« 

 At tinps the folding of the gro'dng leaf sirrfaoe is laore 

 conplior.ted thnr. in the oases disouased aa yet. Figure 82 

 illuatrates a PhytoptuR gall, occtirring on leaves of Fragarla 

 yeeca, 'ffe of ton soe hcTlov; the sac r, ying like fold, protruding 

 ¥roro"tho underside of tho leaf, by uhioh the entrance pore into 

 the sac-cavity is r&'.de smrller. At tines thepse and other mite 

 galls ahow further, often irregular ocnplicatlons in the fold- 

 ing of the leaf mass, 



Sao galls sirdltr to these found on leaves oocur also - 

 "but much '-.aoro rarfly - on Ptalks and petioles. Under the in- 

 fluonOG of the gall stinuli, tho fearJc tissue Bakes a strong 

 surface groFth, breaks, away fr®in the tissue layers lying more 

 deeply and furnlahos a tissue fold of definite form* Exoaples 

 of galls of this kind are found in the branch gall produced 

 by Phytoptus od PrunuR Padna -*-. as alap in the epidermal fold 

 galls irrhioh I-homas observed on Galium^, 



3, TTe vrill terra the third class wa^ed galls because of 

 th© nrturo of their prcduction, 



Walled galls of very diff^^rent form and size are larcduocd 

 by Diptera, Horaiptera Gi;id Hymenoptera (Cynipides), a&iiring the 

 production of the gall, the tissue lying directly beneath the 

 gall animal, or rcther the egg of the future gall-inhabitant, 

 grows tut little, if at all. The ijarta ©djaoent, on the con^ 

 trnry, grow out extra or din^irly strongly. Figure 83 illustrates 

 diagraraatically th development of a walled gall. In a, the ■ 

 round ggg ia visibjr on th>-. vegetative point oit a bud. ],n b, 

 tho edges of the ymng ^all may be recognized, which in jb in- 

 cline toward each fvfchor over tho egg and in d are raiited* 

 (E16) Galle of this kind can be produced on widely^dif ferent pc^rts of 

 the plant, on vege'jativc. points, on stemr and Bta'j.ks, on leaf 

 blades and on roots* Che proc?esRes of growth ore always essen-" 

 tially the same, ev^n rhen many eggs rre deposited near one an- 

 other and each one b->ooaes wa led separately. Figure 84 illus~ 

 %TB'^(to the production of tho \7elX -known bright red spring gall 

 ®^ Cynips termina? is ok the t:'ps of nok branches. Seven eggs 

 are™ visitile which were deposited near one another, A shows 

 the first stage; at B-G the eggs, still partially provided with 

 their long egg sifea.J.kfl/"may te seer to disiippear gradually in 

 the outgrowing tissae, VTith '^everinoh, we will terra "gall 

 plastein" the rapidly growing ''^jbryonic" tissue^, which the 

 gall produces. In the finished gall its own larval cavity is 

 reserved for each larva, TVhile the develppmental course shown 

 in figure 83 led to a one-chambered gall, a multi-chambered 

 form is produced in the raonner illustrated in figure 84, 



The "typical" walled galls here described a*e connected 

 with the "typical" sac galls, moreover, by numerous transi- 

 tional forms. Between the two stand the Sac galls, which are 

 provided with a so-called orifice wall such as are produced 

 by various Phytopti and others. Figure 65A gives a cfiose 

 section through thv^ sac gall of Eriophy es' similis (on Prunus 

 spinnsr ) which originated in the Tea"?. l?Ee~IP^rger, upper part 

 of the gall shows the sac produced by superficial gr<>wth of 



■^ Frank, loc, cit, p, 56. 



^ Aeltere u. ne\ie Beob, ueber Phytoptocecidien, Zeitschr, 

 ges, Waturwiss, 1877, Bd. XLXX, p. 351. 



