V] 



SPHAERIALES 



159 



rotia which originate in the cortex of the host root; reproduction is by 

 means of conidia formed in summer on the surface of the soil, and further 

 by ascospores produced in perithecia. Hartig has found that the perithecium 

 is initiated by the development of a pair of thick hyphae rich in contents. 

 These become enclosed within a mass of vegetative tissue, but their subse- 

 quent behaviour has not been determined, and no details of development 

 are known either here or in other members of the family. 



SPHAERIACEAE : BIBLIOGRAPHY 



iSSo Hartig, R. G er Eichenv/urzeltodter Hosel/ina guercina. Untersuch. aus der forst- 

 botanische Inst zu Munchen iii, p. i. 



Ceratostomataceae 

 The Ceratostomataceae resemble the Sphaeriaceae in most of their 

 characters; they are distinguished by the elongated neck of the perithecium, 

 which is often drawn out to form a delicate hair-like process. The method 

 of liberation of the spores in this family presents an interesting problem, 

 but neither that question nor the development of the perithecium has yet 

 been elucidated. 



A mpkispkaeriaceae 



In the Amphisphaeriaceae the young perithecium is sunk in the substra- 

 tum; as it matures it becomes more or less free, though in contrast to the con- 

 dition in the Sphaeriaceaeand Ceratostomataceae, its base is always immersed. 



Development has been studied in a species of Teichospora and a species of 

 Teichosporella, now both included 



under the genus Strickeria, charac- 

 terized by its muriform spores. 

 The spore produces numerous 

 germ -tubes which give rise to a 

 mycelium of multinucleate cells ; 

 certain cells increase in size and be- 

 come both transversely and longi- 

 tudinally divided till a parenchy- 

 matous mass is produced (fig. 1 19). 

 Other vegetative hyphae may form 

 a scanty investment, but often the 

 perithecium develops without this 

 addition. 



Asci appear as large uninu- 

 cleate cells, and the tissue around 

 them disorganizes. The outer hy- 

 phae become hard and dark only 

 when the perithecium approaches maturity. 



Fig. 1 19. Strickeria sp. ; initial cells of ascocarps; 

 after Nichols. 



