Ill 



^Figure 4S shows part of a cro^s-aection through the 

 so-called window-gall of the maple*'*; a roundish spot of 

 the leaf blade is appreciably swollen, since the cells of 

 several layers of the mesophyll have been greatly enlarged 

 and stretched at right angles to the upper surface of the 

 leaf* The epidermis and usually also the cells of the 

 uppermost palisade layer remain unchanged, the others have 

 become thick, delicately walled sacs, rich in albumen, which 

 usually do not show any chlorophyll content. 



(119) Btore widely distributed than the window-gall of the 

 maple is the reddish brown bladder gall Occurring on the 

 leaves of Viburnum Lantana v/hich is jp^roduced by a USecid- 

 omyine, ^So far as I knov/, this has not yet been felearly 

 defined. "^ {Dhe leaf seems to be distended lense-like on 

 the infected spot, A cross- section shows that the gall 

 surrounds a cavity lined by greatly enlarged mesophyll cells 

 and occupied by the larva* (Compare fig. 43) . The changes 

 in the mesophyll are about the same as those of the maple 

 gall already described. The cells of all the raesophyll 

 layers are soon elongated to about an equal extent. In other 

 cases, the growth of the palisade cells or of the spongy 

 parenchyma cells predominatea, Thus rather irregular cell 

 forms are often produced, as shown in the illustration. In 

 all cases the chlorophyll' content of the hypertrophied cells 

 is extraordinarily scanty, or almost null, but their protein 

 content is very large. Often abundant formation of anthoo- 

 yan-in occurs which malces the galls visible even from a dis- 

 ti^ce. Calcium oxalate glands are not infrequent in hyper- 

 trophied mesophyll. 



Even the pith is able to develop gall«hypertrophi6s. 

 In leaf blades of v/heat, attacked b y Ohlorop s' taeniopus, the 

 cells of the pith grow out into long th-ick villi "whose 

 free ends are much twisted and bent and remind one, by tneir 

 length, of the papillae of many stigmae", Cohn. 



The list of known gall-hypertrophies is not exhausted 

 with those here described. AAn especial group is formed 

 first of all bv the giant cells - in which not only the 

 protein content but even the number of nuclei increases dur- 

 (120) ing cell growth. Multi^nuclear elements are produced, whxcn 

 T^ill be especially discussed in the next division, as tran- 

 sitions between hypertrophj:o and hyperplastic forms. 



A number of other hypertrophies, produced under the 

 influence of foreign organisms, will be mentioned m the 

 following "appendix". ^ ^^_ 



l.^Thomas; Fr. Fenstergalle des Bergahoms. Porstl. Hat- 

 urw, Ztschr., 1895, Bd. Ill, p. 4S9. 



2. V. Schlecht^ndal, Die Galbildungen (Zoo-cecidien) 

 der deutschen Gefasspfl. Zwickau 1891, U. 1150. 



3. Ueber die Bandfiissige Halmfli^ge (Ohlorops taeniopus) 

 Ber. Schles. Ges. Vaterl. Kultipr. 1865, p. 77. 



