SEPT OKI A ClIEXOPODII 31-7 



these widths may on occasion be found simultaneously by examining 

 the contents of one single pycnidium. 



It may be asked how one is to decide between the genera Asco- 

 chyta or DiplQclina on the one hand, and Septoria or Stagonospora 

 on the other. Some might suggest that the two former and the 

 two latter respectively should be more or less merged in one. Apart 

 from their convenience, however, the working m^'cologist knows that 

 they are sufficiently distinct, though he may find it difficult to define 

 the distinction. Such a state of things seems to be not unknown 

 in other branches of human knowledge. 



The required distinction can be found in the nature of the pycni- 

 dium. In AsGochjfta and Septoria the tissue of the very delicate 

 pycnidial wall is composed (except round the ostiole) of slender inter- 

 woven hyphiE wliich wind round one another like intertwined snakes 

 preparing for hibernation. For this- Potebnia has suggested the un- 

 meaning term " pseudo-pycnidial " ; it would be better to call it 

 plectencliy matous. The firmer wall of Diploduia and Stagonospora, 

 on the contrary, is composed of more or less hexagonal (polyhedral) 

 cells, in close contact with one another on almost all sides, forming a 

 tissue known as •' pseudoparenchymatous," a word which under the 

 circumstances might without confusion be shortened to parenchyma- 

 tous. Kound the ostiole, even in Ascocliyta and Septoria, the tissue 

 becomes weakly parenchjnnatous. 



The wall of the fungus under discussion belongs to the Septoria 

 type : the true name and synonymy will therefore be as follows. It 

 will be seen that Saccardo has listed it at least eight times, and 

 Allescher six times. It will of course be understood that no account 

 is taken here of possible biological distinctions. 



Septoria Chexopodii Westd. Bull. Aca:l. ^o\. Belg. 1851, 

 p. 396. Sacc. Syll. iii. 556. AUesch. vi. 756. 



Depazea vagans f. atriplicicola Fr. Syst. Myc. ii. 532. 



Phyllosticia Atriplicis Westd. Bull. Acad. Roy. Belg. 1851, 

 p. 397.' Desm. Ann. Sci. Nat. 1851, xvi. 298. Sacc. Syll. iii. 54. 

 Allesch. vi. 101. 



P. Chenopoilii Westd. Bull. Acad. Roy. Belg. ser. ii. vol. ii. no. 7. 

 Sacc. Syll. iii. iio. 



Ascochyta Atrip)licis Lasch, in Rabenh. Herb. Mycol. ed. i. no. 861. 

 Died. Annal. Mycol. 1901, ii. ISO. 



A. Chenopo'dii Rostr. Bot. Tidskr. 1905, xxvi. 311. Died. Annal. 

 Mycol. 1912, X. 139. 



A. nehiolosa Sacc. et Berl. Bull. Soc. Bot. Belg. 1889, xxviii. 98. 

 Sacc. Syll. x. 305. 



Diplodina Atriplicis Vestergr. BIdr. Kanned Gotl. Swampfl. 

 1896, p. 19, f. 4. Sacc. Syll. xiv. 952. Allesch. vi. 679, fig. 



B. Chenopodii Karst. in Hedwig. 1885, p. 73. S.icc. Syll. x. 315. 

 Allesch. vi. 682. 



Septoria Atriplicis Fckl. Symb. Myc. p. 3D0 (1869). Sacc. 

 Syll. iii. 556. Allesch. vi. 737. 



S. Westendorpii Wint. in Hedwig. 1887, p. 26. Sacc. Syll. x. 

 380. Allesch. vi. 756. 



2b 2 



