110 



out Into delicate, muoh branched and intert^tlned threads , 



• * 



The ground tispue of plants partiolpates differently 

 in the oonstruotion of the galls » In many-gall forms Its " 

 elenents are only enlrrfred, rithout division (Hypertrophy), 

 in others very abundant cell division? uauully follows gronTth, 

 I7e are oonoerned at present only with ohf-nges of the first 

 kind. 



It is easy to narae a large titiiBber of fungus or jlnsect 

 galls in the production of v/hi-oh, for example, we find that 

 the raesophyll of the leqves reaot by developing abnormally 

 large cells bxit to the exclusion of all processes of i division. 

 In almost all oases, hovrfver, those galls are not involved 

 here, the oharaoterr of which depends upon the produojbs of 

 purely hsrpertrophic changes, but those In which the teuission 

 of cell division is to be observed only as Indication of an 

 incomplete development ef the diseased form.fi Undernfmore fftv- 

 orableT.externr-l conditions gall hyperplasias instead of gall 

 hj^rtrophles would have been produced by the same parasites , 

 (118) We will defer the consideration of these galls to the next 



chapter and limit ourselves in the present to those, in which 

 in accordance ^ith the specific poisonofus effects - only 

 hypertrophic cell-changes are always oonoerned and only 

 through these is produced the characteristic structural form 

 of the gall-tissue* Phenomena of growth of the kind described 

 own be caused by animal as well as by vegetable Symbionts, 



As first instance, I will name those changes which are 

 caused by Anabaena Cyoadearum on the roots of the Cycadeae^, 

 In a definite zone, the cells of the fundamental tisane grow 

 out into sacs elongated like palisade cells, which le§ve 

 free large intercellular spaces. The Anabaena threads re- 

 main in these* (Cmspare fig, 41), 



Of the native Zoo-cecidia tV70 fly-galls demonstrafe 

 estcellently the process of growth here described. 



Ireltgeb, Lebermoose, Bd. V, p, 16., 



^ Similar oon.*5iderations were giveij above (p, 97) in 

 the discussion of callus hypertrophy, 



^ Most important literattare: Reinka MOrphol, Abhandle, 

 p, 12, 2wei parasitisohe Algen. Bot. J5eitg. 1879, XXXVll. 

 p, 4t2« Sohnelder, A* Mmtualistic symbiosis, of algae and 

 bacteria with Cycas revoluta. Bot, (Jass,, 1894, Vol> XIX, 

 p, 25. (Joebel, Organographie. 1901.. p. 483. Life Juber- 

 like rootlets of Cycas revoluta, Bot, (5fta. 1901, vol. xxxi, ^.^ 

 p. 265. Pampaloni 1, e, Hostoc punotiforme nei suci rapporti 

 col tubercoli radlcali delle Cioadee. H. Giorn Bot, Ita-,, 

 1901, K» S. Vol, VIII, p. 626. 



