200 THE ASCOMYCETES 



Chaetomiaceae. As their name indicates, the members of this 

 family are distinguished by fructifications the exteriors of which 

 are partly or completely beset with hairs. They occur on paper, 

 straw, dung, and decaying plant tissues and are known to be 

 capable of digesting cellulose and therefore of functioning in the 

 formation of humus. Chivers (1915) in his monograph recog- 

 nizes 114 species and 14 varieties of Chaetomium and 2 species of 

 Ascotricha. Species of Bommerella are regarded as belonging to 

 Chaetomium. Chaetomidium lacks an ostiole and thus shows 

 affinity with the Plectascales. 



The ascospores, which are freed by early deliquescence of the 

 asci, are brown to black and t\^pically lemon-shaped. 



Conidia are commonly borne on the hairs which adorn the 

 perithecia. Various conidial forms have been observed, most of 

 them belonging to the form Genera Sporotrichum and Verticil- 

 Hum. In Ascotricha chartamm there occur not only a Spor- 

 otrichum stage but also a peculiar chlamydospore stage, which 

 was described as Die y ma ampidlijera. 



FiMETARiACEAE (Sordariaceae) . The Fimetariaceae are sapro- 

 phytic species, most of them occurring on dung. Some are lim- 

 ited rather closely to the dung of certain species of herbivors. 

 Their perithecia are flask-shaped, the perithecial walls being 

 membranaceous. The ascospores are typically unicellular and 

 are provided with a gelatinous sheath or one or two gelatinous 

 appendages. By means of this gelatinous coating the ascospores, 

 which are forcibly discharged, adhere to vegetation. They are 

 ingested by browsing animals and hence disseminated by them. 

 Conidial stages are rarely found. 



Among the better-known representative species is Pleurage 

 anserina. This species is normally four-spored, but occasionally 

 five-spored asci are seen. In four-spored asci the spores are bi- 

 nucleate; in five-spored asci the spores differ in size, two of them 

 being small and uninucleate. The binucleate spores, when grown 

 in monosporic culture, are hermaphroditic and self-fertile, as 

 found by Ames (1934), whereas the small spores are of two 

 classes, which Ames called A and B. Monosporic cultures from 

 these small ascospores bear both ascogonia and spermatia but are 

 self-sterile, although, when reciprocally crossed, they are fertile. 

 In regard to this fungus, therefore, it is not proper to speak 



