EFFECTS OF 1'AKAMTIC Fl'NGI ON TlsM'Ks OF HoM. 43 



the witches' brooms due to A> fi.il in m /////////////, the jiitli appeal - 

 enlarged as the result of increase of the medullary parenchyma. 

 In diseased leaves, palisade parenchyma can frequently no lon-ei 

 be distinguished from spongy, and only irregular polygonal cells 

 are formed. As examples may In.- ui\m needles of tir with 

 Aeddium nJiiffim/m, and leaves with ualls dm- to K\oa-ceae. 

 Finally, there may be a marked increase of wood-parenchyma, 

 lioth of medullary rays and the wood proper; this is especially 

 wdl marked in Juniperus communis atfected by Gymnosporangium 

 juniperinum? where inconsequence of an enormous increase of 

 the parenchyma of rind and medullary rays, the tracheidal 

 regions become separated by broad wed^e-shaped rays, and at the 

 same time they are peripherally intersected by bands of pan-n- 

 chymatous tissue resulting from increased development of the 

 wood-parenchyma (Fiy. 220, etc.). 



The Sclerenchyma is generally suppre.-.-ed where hypertrophy 

 oeeurs. Kxamples mentioned by Wakker are stems of cowberry 

 with A'>i'l>tixi'/i/>//i, of hawthorn with Gymnosporangvum, of 

 Sanguisorbia with Zenodochus, and alder catkin-scales with 

 Erunxms. ( )n tlie other hand, sclei-i-iiehyma is developed iii 

 stems of Cirsium as a result of I'm-i-inin suaveolens, whereas 

 normally it i> absent. 



The .secondary vessels of the wood frequently remain irregular, 

 and with imperfectly absorbed partition-walls. AccordiiiLi to 

 Wakker, this is the case in [""<</,/////// with A'.<nl>,ist</i/i/i/, 

 d-nhi,!/!!* with Jlisftli<i. and Jth ///////> with Ax-ulimn. 



Supjre<si(in of interfascicular cambium was observed by 

 ^'akker in buckthorn and nettle with their re-pert i\v Aeddium 

 para-ite-,. I'rolon-ed activity of the same tissue he found in 



v ////////////// with (.'//xfnjiitx. 



Arrest of lignification was found by Wakker in medullary ray- 

 of Orataegus with J t '< */<//<>, and in deformed scales of alder 

 eatkin> atfeeted by /;.-V///S- ( /N. 



\\'- have already considered increased -rowth in leu-th and 

 thickne.-- in connection with li\ pert i oph\ . It need only be 

 added that increased thickness of \\oody plants may be due to 

 increase of the rind, the bast, tin- pith, or medullary ra \ .-, and not 



1 I'. \Vi n|.-. ,\ ii:i!<iini>' In- I 'nti-i -IP IHIIIL: il. i In i .-I i Gymnosporangium-Arten 

 ln-r\ MI ^i-i iifi-ni-ii Miasbildungen ln,iii'_ l>i->., Miiin-ln-ii. |s|it ; also, / 



, a-, ,,. '/., it ,,-1,,-ii'i , 



