NECTRIA 



179 



brittle. Experiments have proved that the ascospores when 

 placed on the young leaves, germinate, enter the tissues, and 

 give origin to the disease. 



Ascigerous form. Stromata flattened, developed on the 

 under surface of the leaf, reddish, then orange-brown, ostiola 



Fig. 46. Polystigma rubritm. 1, diseased plum leaves; 

 2, section through stroma showing perithecia ; 3, asci containing 

 spores ; 4, spermatia produced in spermogonia. Fig. 1 reduced; 

 remainder highly mag. 



sunk in the tissue ; asci clavate ; 8-spored ; spores elliptical, 

 obtuse, straight, subhyaline, 10x6 fx. 



Conidial form ( = Lil>erte/la rubra, Bonor.). Spermatia 

 filiform, slightly thickened at one end, curved, 30 \i long. 



Prillieux, Ma/ad. des Plantes Agric, 2, p. 91 (1897). 



B. Spores hyaline, \-septate ( = 2-ce//ed). 



NECTRIA (Fries.) 



Perithecia distinct, clustered, or scattered, sometimes pro- 

 duced on a fleshy stroma that has previously borne conidia, 

 fleshy or sub-membranaceous, clear coloured, usually red or 

 orange ; asci cylindric-clavate, 8-spored ; spores hyaline, 

 elongated, 1 -septate. 



