SPHAERIALES 



265 



better placed with the Sphaeriales as by Arnaud (1910, et seq.). As they 

 are extremely pleomorphic and often several genera appear adjacent or 

 intermingled on the same substrate, only extensive cultural investigations 

 can make clear their forms. 



Pleosphaeria Citri (Limacinia Citri) in the Mediterranean region is an 

 epiphytic, sooty mould on the leaves and twigs of Citrus, Nerium, Laurus, 

 etc., and especially luxuriant on the honey dew of leaf lice. The myce- 

 lium is comparatively light colored, developing, according to growth 

 conditions, to a thin subiculum on which rest the pycnia and perithecia, 

 or to a luxuriant but loose subiculum in which are embedded the organs 

 of fructification. Both the pycnidia and perithecia are surrounded by 

 erect setae. A view of the structure of the perithecium is shown in Fig. 





Fig. 176. — Limacinia spongiosa. 1. Section of perithecium and subiculum (X200). 

 Teichospora meridionalis . 2. Perithecium with disintegrating subiculum (X200). 3. 

 Ascospore (X 670). {After Arnaud, 1911.) 



176, 1, which gives a longitudinal section of a species closely allied to 

 Pleosphaeria Citri, the also epiphytic Limacinia spongiosa; it is to be 

 observed that the perithecia are still normally embedded in the flat 

 subiculum. 



In other genera there appears a peculiar tendency, as in many Myri- 

 angiales, to raise the perithecia on plectenchymatic protrusions above the 

 stroma, which thus is differentiated into sterile basal and fertile columnar 

 parts. A schematic cross section through a similar transitional form, 

 Teichospora (Capnodium) meridionalis, also on Nerium and Citrus, is 

 shown in Fig. 176, 2. Under suitable growth conditions, its subicular 

 hyphae swell and in damp air become slimy, adhere in a slimy stroma 

 which occasionally exhibits very bizarre forms. 



We may consider as an end form of this developmental series Teicho- 

 spora {Capnodium, Apiosporium, and Fumago) salicina, a black 



