3, AsslMJlatory gisaue 2X8 



One charaoterlstic of pl-most ill galls in their poverty in 

 chlorophyll. Very wrny prosoplrsratis to "be sure are a prle gre^ii 

 such ae the hr.lf-trarisparont produots of Spathegaster bacoarurri ; 

 Hormonyia fa p:i. etc., Imt their ohloroplasts' are s'6anty, ama^l, 

 wisteA and only weakly colored. In very many, ' stich as the 

 various elliptical galls, the 0?erminalig'', Folii, etc, no chloro- 

 phyll at all raay he found under the Microscope at the time of 

 ripening, 



• « 



The gall of Kematus Vallisnerii (on Salix) , for example, 

 should he considered an exception ^ the rule, iThen a gall of 

 this kind is brok'ozi open, the extensive deep green tissue con- 

 plex inside it is strikingly noticeable even mrcrosoopicGlly. 

 The outermost layers? consist either of elements elongated into 

 (256) a palisade form, or roundish ones as clear as water. Then, 



to\7ards the inside, comes a thickly developed, assimilatory par- 

 enchyma (compare also figure 88), which is far stronger than the 

 normal mesophyll of the willow leaves. 



The large galls of Aulex Glechomae . rich in water, which 

 deform leaves and stalks, develop superficially an assimilrtory 

 tissue which ia pale green in color and cSnsists of one or more 

 palisade layers. 



In the sac galls, which Phytoptus maororrhynohus usually 

 produces -vbtit abundantly on the lekves of Acer Pseudo-platanus , 

 a large -celled, oolor^.esB parenohjTna or one containing anthocy- 

 anin, is formed on the outer side (the morpho logical upper side 

 of the leaf) and on the inner sjde (the morphological under side! 

 a cell layer which, pale green in color, resembles a palisade 

 tissue (fig. 117). 



Cases are not really rC-te in which the galls carry over un- 

 changed the assirailatory tisf?ue of the organs which bear them, 

 (many stalk and leaf galls; compare, for example, figure 93). 

 Since products of pathological tissues are not concerned in 

 these, we may pass them by, 



4. Vascular. Tissues 



The relation of the galls to the vascular bundles of the 

 plants which becir them is unmistakable, Many are produced di- 

 rectly from the ^tissue of the vascular bundles, others are con- 

 nected throughout with the neighboring vascular tracts. The 

 vascular bundles are usually very sparsely formed, and only as 

 delicate cords, inside the galls themselves,- in kataplasmas, 

 as in proBoplasraas, 



The individual elements of the vascular bundles resemble 

 normal ones; jret the individual ducts usually have very narrow 

 luinlna. Traoheids abound and, for their part, often repeat the 

 form 63P the parenchyma cells. In many galls,- for example, in 

 that of Spathegaster baooarum .- the composition of the vasctilar 

 bundles and the iforra of the separate tracheal elements resemble 

 throughout the corresponding cells of many callus tissues. 

 (Compare fig. 67), 



(856) The structure of the vascular bundle s likewise in general 



is similBr to the normal one. The galls of Andrious a lbopuflcta- 

 tus and Trigonaspis megaptera should be nameoasexceptions , 

 which, according to "SevSr incii (loc. cit, p. 128) have concentric 



