(234) 



205 



fl^ltllTL'^tll^lJ''' '^Jj^iji^- tissue"ft Ly rate b.^ne 

 furnished by the hairs, the filling of which f.Mth str.rch 

 oil etc, was discussed above. The bladder Rails of 

 I.f-^23ura__I^;am are for the most pa*t composed of nptrl- 

 • tive cissue (compare p. 119), 



Besides the differences separating kataplasmas from pros* - 

 plasmas, some characteristics com mon for all ealls should be 

 mentionedT^ '—- — • ° 



^}^^^ ^11. ^^^ tendency, to formparenchyma is striking; 

 the galls are almost entirely parenchymatlc structures. To 

 be sure, ducts may be found in them, but these ducts themselves 

 are composed of parenchjmiatic elements. The lack of libriform 

 fibres in all gall formations, even the most highly organised, 

 IS very noticeable -i-. in these negative characteristics, the 

 prosoplasmas conform to callus tissues, wound wood and kata- 

 plasmatic galls. 



Further, the suppre ssed retrogres sion in the formation of 

 tracheal elements is conspicuous; galls generally co'nl&aTn only 

 very scanty vascular bundles, the ducts usually having narrow* 

 lumina. Similar conditions are found in kataplasmas, where the 

 production of parenchyma also retards the formation of tracheal 

 cell -forma. 



The same is true of the scanty chlorophyll content of 

 galls. They are as pale a green as many fungus galls most 

 callus tissues, etc. In many the green pigment is entirely 

 lacking. 



We T/ill herewith pass over to the discussion of the dif- 

 ferent kinds of tissue forms in galls a nd will begin with "The 

 two most important , tlie protective and nutritive tissues. As 

 less inportant, the sparsely developed fibro-vascular , the as- 

 Bimilatory tissue and a few others will be named later.' 



1. PROTECTIVE TISSUES 



As the protective tissues of prosoplasmas, there come un- 

 der consideration, the c ov er ing tissues and, also, especial 

 complexes of stone cells. ' Vifo wii:). term the latter mechani<sal 

 tissue. No ahsolutely sharp line can be drawn between both 

 forms "of protective tissue because many peripheric cell layers 

 in galls, including the epidtrrais, are often composed of simi-^ 

 lar elements, resembling stone cell,s. 



Epider mal Tissue 



rfiiwoi '■■ ■■■*! I'll"*;! " ■ . <T n i> ii i iiii ii.i^Na,t»wi» 



At this poiijt, the epide rmis comes under our oonsidera- 

 tion, .only in so far as it performs the fur\ctioiis of a cover- 

 ing tissue and, by means of an unbroken covering, ^ strong 

 cuticle or because th6 production of hairs gives proteqtion to 

 the more deeply lying tissues, (The epidermis in sfto and walled 

 galls* which lines the oavity of the gall, has other functions 

 and will be disciissed later,. Further, we will have to discuss 

 (235) only tj^ose forms of epidermal tissues which in gall-prpduction 

 are not carried over in an unchanged form from the normal parts 

 of the plant, bearing the galls, as is the case in many medul- 

 lary galls, *but which in some way vary from the norrnal in their 



•*• Compare here statements on p. S46 on the gall of 

 Synophrus , 



