212 



also p^od^^ced here ronnd about the v/hole, (Mg. 1087}. In 

 the leaf-ourline ^all of Pemphlf^ua mllidus rnd in others, the 

 up-curled edge of the leal is pressed so firnl- against the 

 lamina, th£!.t the shaft for exit scarcely comes"' under considera- 

 tion in the action of the mechanical tisHue develop e<^ in the 

 leaf tissue (Pig. 108G). Ab an exception to the ru> the gall 



«'f,Oja°iMiZiaJJLZ-i^£Se ^^ig- 108G) should be nair^d. Ylhile the 

 gall itself resembles a bi-convex lense, its mechanical mantel 

 has the form of a spindlo or a helmet; its long -axis being 

 perpendicular to the medial plane of the gall. 



The casofi deserve speoial mention, in which the mechanical 

 mantel is composed of tv/o parts. Instead of a hollow ball, it 

 (245[ here i-esonblea two hollov/ hemispheres with overlapping edges 



Of with edges almost touching e^ch other. The gall of piplosis 

 globu^ i. noi; rare on rspen leaves, opens on the uhderside by 

 means of a narrow cleft. The lov/er part of the mechanic".! man^ 

 tel (Pig, 108H) begins immediately at the cleft and, like a 

 bowl set upright, oncloses the under te-lf of the larval chamber. 

 The second half of the mantel lien Gomm^rhat bent over this;- 

 and, like a hemisphere, protects the upper part of the gall 

 cavity. Between thCvse two parts of the mechanical tissue, 14es 

 - . a thin-wnlled parench^nna. The galls reproduced in ftgilres 90 

 (246) aj^ 111 show very similar conditions; in them the upper part of 

 the mechanical tissue has asRuned the form of a I"fat lid. 



Usually each gall possesses imly one mechanical mantel: a 

 further advance is shorm whea?e a second one surrounds the first. 

 While the inner mantel is usually closed on all sides » the 

 outer one is often only half formed;- it then lies like a flat 

 pan over the inner one and over the central gall cavity. (Pigs. 

 104 and 108D). The structure of the ash gall of Diplosis bot- 

 ^laria (fig. 1081) is eapdcially firm. On the complete inner 

 mechanical mantel is laid an outer one which is open only on 

 top, showing in cross-section a horse-shoe form. Often both 

 parts, lying opposite the gall opening, unite with one another. 

 In other cases, the OTiter mantel also forms a closed whole, as, 

 for instance, in the Banif^teria gall (fig. 108E), or in that of 

 Cynips Mayri (Pig. 109), In the latter we see clep.rly that the ' 

 outer mechanical mantel repeats well the form of the ivhole gall, 

 while the inner one assumes a simpler spherical form. 



If two mechanical tissue mantels are fortnecl in the same 

 gall, the two may almost alvirays be distinguished more or less 

 from each other by their histology. 



A very peculiar kind of Gynipides gall is represented 

 by Synophrus politus . On branches of (^uercus Super , etc. 

 j^ small inner cavity encloses the larval! Its anatomical 

 O"tr*iotur0 la ^orj.'B.iiTt'kiri^.-i The protective tissue of the 

 galls if formed of a thick woody-mantel v/hich represents a 

 xylem kernel surrounded by bark, but apparently completely 

 isolated from it, similar to the tuber gnarls spoken of 

 aJfoVe. The galls also correspond histologically to these. 

 Kfe find in abnormal wood, composed predominantly of pittec" 

 parenchyma, that there are places v/ith normally arranged 

 elements IjT-lng side by f'ide with others who^e fibres, in 

 the greatest "disorder" take first one direction, than an- 

 other, Also the beginnings of "gnarl formations" xvith 

 strangely bent libriform fibres are not lacking. YJe often 

 find large sclereids '»vith large lumina and strongly thick- 

 ened walls in the immediate vicinity of the larval chambers, 

 Unfortunately in the dried Material I investigated the for- 

 mation of the nutritive layer was no longer recognizable, 



