The Life History 0/ Pol\-thrincium Trifolii Kuuze. 223 



size and reaches nearly to the surface of the stroma, appearing 

 in surface \-iew as a whitish spot in the black stroma. After 

 attaining the t^-pical pear-shaped form these cells graduallv 

 disintegrate and many minute oil drops are often to be seen 

 exuding from the ostiole which is formed at the apex of the 

 pycnidium at this time (fig. 5). Many of the oil drops are curved 

 and resemble small spores. They were probably mistaken for 

 the pycnospores by Fuckeldn who does not give their size, but 

 merely comments on their minuteness and their Brownian move- 

 ment. The hning layer of cells produces on its inner surface 

 very many ampulhfomi cells, which may be considered to be 

 conidiophores. Ampulhform conidiophores similar to these occur 



Text-fig. P\-cnidia] stroma cut through pycnidium bearing pycnospores. 



X 215. 



in many Fungi and also in Lichens. From the ampulhform 

 conidiophores long chains of oval conidia are formed in basi- 

 petal succession. The entire pycnidium becomes filled with 

 conidia embedded in mucilage, which will absorb water and 

 swell up, thus extruding the spores in the form of a tendril 

 through the ostiole. 



In hanging drop cultures in tap-water and weak cell-sap 

 extract pvcnospores merelv budded hke yeast; budding was 

 obser^-ed also on infected leaves, as well as germination in the 

 normal manner. 



In October, 1921. plants of Trifolium repens, gro^^ing in a 

 field were infected with pvcnospores which after being stirred 

 in a drop of sterile water were transferred by means of a fine 

 brush to the under-surfaces of leaves in various stages of growth. 

 After three weeks most of the leaves showed the characteristic 

 black stromata bearing t\-pically waved conidiophores with 

 large obovate uniseptate spores; several also showed pycnidial 

 stromata in early stages of development. Mild autumnal 

 weather with occasional showers of rain prevailed throughout 



15—2 



