GNOMONIACEAE 219 



rhodina. Sexuality in species of Physalospora has never been 

 investigated. 



Attention may well be directed to the fact that the ascospores 

 of some species of Phvsalospora have been described as hyaline 

 and those of other species as yellowish. Hesler (1916) states that 

 those of P. cydoniae are yellowish. There remains the likeHhood 

 that all species having Sphaeropsis, Diplodia, or other conidial 

 stages with dark spores will be found to have pigmented asco- 

 spores. Mature ascospores must be examined. 



Ophiobohis. The most important member of the Genus Ophi- 

 obolus is O. cariceti var. graviiniSy causing take-all disease of 

 cereals and grasses. This disease was first reported in the United 

 States in 1920 but was known long before that date in Australia, 

 Europe, and Africa. Its causal fungus was first described as 

 Sphaeria cariceti from England in 1861. Essential facts regarding 

 the disease are contained in a report by Kirby (1925) and regard- 

 ing the development of the pathogen in a report by Jones (1926). 



Ophiobohis cariceti produces spermatia, which Jones regards 

 as functionless, in association with perithecial primordia contain- 

 ing coiled ascos^onia. Thev too are regarded as abortive, and 

 fertilization is apogamous, involving vegetative cells. From these 

 conjugated vegetative cells the ascogenous hyphae arise. Nuclear 

 fusion is not antecedent to ascus formation, and meiosis occurs 

 with the first division of the primary nucleus of the ascus. Since 

 Gjiomojiia erythrostoma has a similar type of development, Jones 

 suggested that O. cariceti be placed among the Gnomoniaceae. 

 In the opinion of the present authors both of these organisms 

 should be reinvestigated in regard to the function of spermatia. 



Gnomoniaceae. The Gnomoniaceae resemble the Myco- 

 sphaerellaceae in that their perithecial walls are of similar texture; 

 the perithecia of both are embedded within the substratum, but 

 those of the Gnomoniaceae have ostiolar necks that project much 

 more prominently. The asci of Gnomoniaceae possess thick 

 apices provided with a canal. Gnomonia and Glomerella, both 

 of which contain a considerable number of destructive plant 

 pathogens, have been extensively studied and are worthy of more 

 than passing mention. Their conidial stages, belonging to the 

 imperfect genera Gloeosporium, Colletotrichum, and xMarssonia, 

 produce diseases known as anthracnoses. The conidia of anthrac- 



