The Life History 0/ Polythrincium Trifolii Kunze. 227 



Systematic Position. On account of the fact that the asco- 

 spores are uniseptate and the cells equal in size the fungus is 

 best placed in the genus Dothidella. 



DOTHIDELLA TrIFOLII 



Status conidicus. Polythrincium Trifolii, Kunze — stromatibus 

 in pagina aversa folii atris, carbonaceis, punctiformibus, deinde 

 coalitis. Conidiophoris tortuosis, exquisite undulatis, fuscis, 

 eseptatis, fasciculatis, erumpentibus, conidia singula, obovata 

 brunneola, uniseptata, 20-22 x ii-15/Lt, apice gerentibus. 



Status pycnidicus. Sphaeria Trifolii Pers. — Stromatibus com- 

 pactioribus, obscure fuscobrunneis, pseudoparenchymaticis ; 

 ovalibus, achrois, hyalinis, 5 x 1-5 )u, conidiophoris papillatis 

 suffultis. 



Status ascophorus. Dothidella Trifolii — Peritheciis in stro- 

 matibus iisdem vel similibus evolutis, ampullif ormibus ; ascis 

 e basi oriundis, clavatis, leviter flexis, 8-sporis aparaphysatis. 

 Sporidiis plus minus biseriatis, irregulariter fusiformibus, 

 achrois, i-septatis, 24-26 x J-Sn, loculis aequalibus. 



Hab. in pagina aversa foliorum Trifolii repentis, Tanworth- 

 in-Arden, prope Birmingham. 



General Conclusion. 

 Polythrincium Trifolii develops a rather loose stroma on the 

 under surface of leaves of Trifolium repens and produces during 

 the course of its life histor\' more compact and deeply seated 

 stromata, which bear pycnidia containing pycnospores [Sphaeria 

 Trifolii Pers.) capable of infecting fresh clover plants. These 

 stromata, on the decay of the leaf, fall to the ground and function 

 as sclerotia. On further growth perithecial cavities are produced, 

 containing the asci and ascospores characteristic of a Dothidella, 

 and not of Phyllachora as has been assumed by various authors. 



In conclusion we wash to express our sincere thanks to 

 Mr W. B. Grove, M.A., and to Professor Yapp for much valuable 

 help and criticism during the course of this work. 



Postscript. 

 Since the above was submitted for publication a paper by 

 Ch. Kilhan entitled "Le Polythrincium Trifolii Kunze parasite 

 du Trefle" has appeared in Rev. de Path. Veg. et d'Entom. 

 Agric. X, pp. 202-219 (1922). According to this writer the 

 perithecia commence to develop at the same time as the 

 pycnidia. The development of the perithecia is very slow but 

 may be accelerated by burying infected leaves in fine sand in a 

 warm atmosphere and watering daily; if, on the contrary, they 

 are placed out of doors on damp cotton wool development is not 



