242 BOTANICAL GAZETTE [October 



by cross, diagonal, and longitudinal divisions, and continue to 

 swell and send out short hyphal branches by budding (figs. 69, 70). 

 This body increases in size, becoming darker in color. Branches 

 from adjoining cells or closely lying hyphae may interweave with 

 the branches from the mass, at length forming a primordium (fig. 71) . 

 from which a pycnidium develops. Usually this primordium arises 

 from a single main hypha, but occasionally 2 or more contiguous 

 h3^hae are included in its formation. The mode of development 

 is meristogenous, with small hyphal branches at times included in 

 the formation. Both simple and compound modes are found, but 

 the compound mode seldom occurs. 



Coniothyrium, species indet. ; culture procured from the air 

 of the laboratory in the summer of 19 17 by W. S. Beach. 



A few adjacent cells in a single hypha divide into shorter cells. 

 These cells branch profusely (fig. 72). A few of the cells continue 

 to divide and swell, and the branching hyphae divide and branch 

 (fig. 73). The whole becomes a more closely formed mass (fig. 74) 

 which forms a globose, dark brown, finely reticulated primordium. 

 From this the pycnidium develops. The mode of development is 

 simple meristogenous. 



The genus Coniothyrium, so far as studied, presents only the 

 meristogenous development. 



Septoria Fries 



Septoria polygonorum Desm. ; isolated from its host Polygonum 

 persicaria L. at Urbana, Illinois, July 191 6. 



The development of the primordium in most cases is by the 

 usual meristogenous method, but in some instances it is atypical. 

 Some of the primordia arise from a single hypha, i or 2 cells of 

 which divide transversely and diagonally, and, swelhng slightly, 

 continue to divide (fig. 75). Later this mass develops into a 

 globose, finely reticulated, pale brown body. In some instances 

 the compound mode appears in which 2 or more hyphae are 

 involved in the formation (fig. 76). In other cases primordia 

 are to be found arising from a main hyphal strand with numerous 

 branches of nearby hyphae intermingling in the mass (fig. 77). 

 This involves both the meristogenous and the symphogenous 



