SPHACELOTHKCA. 



303 



this fungus as follows : ' " Sphacelotheca forms its compound 

 sporophore in the ovule of its host. When the ovule is normally 

 and fully developed in the young flower, the parasite, which 

 always grows through the flower-stalk into the place of insertion 

 of the ovary, sends its hyphae from the funiculus into the ovule, 

 where they rise higher and higher and surround and penetrate 

 its tissue to such an extent as 

 almost entirely supplant it, and 

 thus an ovoid fungus-body of 

 densely interwoven hyphae takes 

 the place of the ovule. The 

 micropylar end of the integu- 

 ments alone escapes the change, 

 and remains as a conical tip 

 (Fig. 164 C) on the apex of the 

 fungus-body and gradually turns 

 brown and dries up. The fungus- 

 body is at first colourless and 

 uniformly composed of much- 

 branched hyphae, which are 

 woven together into a compact 

 mass and have the gelatinous 

 walls of the simple sporophore of 

 Ustilago to be described below. 

 If it has retained its ovoid 

 form as it steadily increased 

 in volume, differentiation begins 

 first in the apical region into a 

 comparatively thick outer wall 

 which is closed all round, an 

 axile columnar cylindrical or 

 club-shaped body, the columella, 

 both parts remaining colourless, and a dense spore-mass which 

 fills the space between the two and becomes of a dark violet 

 colour (Fig. 164 C, D). The lower part which corresponds to 

 the funiculus and chalaza of the ovule remains undifferentiated, 

 and an abundant formation of new hyphae is constantly taking 

 place in it. This new formation is so added from below to 

 the differentiated portion, that the latter constantly increases 

 ^ De Bary, Morphology and Biology of the Fungi, English Edition, p. 173. 



Fig. 164. — Sjphacelotheca hydrojiiperis in the 

 flower of Polygonum Hpdropiper. A, Ripe 

 compound sporophore of the fungus project- 

 ing from the pei-ianth of the Polygonum. 

 E, The same, with the mass of spores emerg- 

 ing from the sporophore. C, Median longi- 

 tudinal section through a young fructifica- 

 tion and its environment. B, Longitudinal 

 section through an older sporophore. c, The 

 columella, p. The perianth. /, The wall of 

 the ovary, o, The integument (micropyle) of 

 the ovule, g, The style. In C and D the 

 sterile or young tissue of the fungus is 

 shaded by longitudinal lines, the mass of 

 ripening spores is darker. Further explana- 

 tion in the text. (Slightly magnified.) 

 (After De Bary.) 



