rilKDINEAK. 331 



The different forms of spore may lie found on one ami the .-aim- 

 host-plant (autoeciuus Uredineae), or the aeridiospor.-. ami 

 pyciiidial conidia may frequent a different host from tin- uredo 

 and teleutospore-forins (heteroecious Uredinea>-i. : 



A mycelium may In- produced from tin- ucnuinatini; aeejdio- 

 spores, uredospoivs, or sporidia. It spreads throughout the 

 intercellular spaces of attacked organs and causes thickening, 

 distortion f the tissues of its host, or the format inn ut' " witches' 

 broom>." Xutriment is frequently ohtaineil by means of cone- 

 shaped or button-like haustoria in the interior of ho>t-< ells. 



Hihei nation of rust-fungus is most commonly attained through 

 the telentospores, the thick coats of which make them peculiarly 

 suited to pass through a lengthened resting- period. Some foim<. 

 however, hil.ernate hy uredospores, by aecidiospores, or by the 

 mycelium remaining on m- in living perennating stems, twigs, or 

 underground rootstocks of their ho>t. 



Accjdiospores on germination produce, as a rule, a mycelium 

 which gives rise to uredo- or t>-lcntospores, rarely to aecidiospm >- 

 ('.//. run-in in senecwnis ami Uromyces ervi)? Credo-pores on 

 UcrmiiiMtion. produce a mycelium from which uivdo>pon-s are 

 first -iven off, then teleutospores. The sporidia of tcleutosjmres 

 ui\e ri-c to a mycelium which frequently produces pyciiidia 

 and aeeidia. hi rare cases, the sjinridia of species, which normally 

 fnriu aeeidia, aiv >aid to develop a uredo-inyceliimi (e.g. I'm;-. 

 I/fir mini* according to 1'lowri^ht ). 



Tin.- I'l-edineae ai'e for the most part sti'ict parasites, and 



exhibit marked adaptation to their respective host-plants. Seveial 



of the polyxeliolis member- frci|llelll ill- several SpeClCS of l|o>t- 



plant have been found to vary a-cordin- to their habitat, so that 

 one and the same Species assumes a -li-htly diffei-ent form on each 



'Tin- |ilirliiiiriiiiii nf ln-ti-i-nci-i.-iii \\.is till i|llitr I cci'iil 1\ klln\\ll iinly aniiilii:^t 



t In- I'M. U'c in HI in ;iinl \.i\v ,i -i-li in h,i\ i-. hiiui-\ ri , n-i-nit ly pointed OUl I li-it 



in >''/.,-,,//'/,/// /,,/,. .,IM- of tin- .\^'-iiinyi--tc- i|>. 'JTTl. I IK- i-iniiilia '! 



tln^ tpeciei re |IMI.|IICI-,| only mi l'ti<->-ini>i/n ii/i'iiini^>i/,i, tin- a|in(ln-i-i.i mils nil 



L''linn, .iliil alli-l nati- \\itli i-.i.-li iitlii-r, tO tlial tin- I. "linn ran lie intrrl 1-1 1 nlil\ 



rininat inu' mniilia, t li-- \'- * in nm \\\ m-i niinat IIIL; OSCOSpOl 



hn-ti-l ( .\ntii ri't,,-<-h. !';/// /// Vfini'i. l>'Mt |ininti-il mil turtlh 



kihil. ill \\liirh ai-rjilla \vrri- pi i M I nn-il tin- MIIIIIIUT t In i iiiijli. ali'l ln> 

 in i !' i- 1 1" i . while in atltumn ti-lnil i-|n n - u n < fiinnnl. Hi- lia> mm r i ri r nl 1\ 



-iH-ial n>nrlii-iiiii (Flora, ivi.i, p. :i'.Ui; thai \\nli tln--i- specii 



I . \\liirh |irni|i|ri- ai-riilia an. I t i-li-nl 1 1-|.. n r . l.nt im UFI 



|i'i|- 'In- .n-rjil , i|i:llilf nt I i-|iriii|lli-||| L ' ,u-r|ili.i \\ln-ll tin |M-| i-Mll.ltlllJ 



mycelium i \>-.< enl -innlarl\ \\iili ilii.-i- ! gpeciea \\liirli | Inn- a verj 



!l MMMilii-r "t nn-ilii^M.: 



