114 Transactions British Mycological Society. 



Chlamydospores. Reinke and Berthold refer to these as 

 macroconidia and to the fusiform conidia as microconidia, 

 following Tulasne's terminology. As a matter of fact the 

 chlamydospores are smaller than the conidia, and there seems 

 no adequate reason for retaining these somewhat obsolete 

 terms. There is practically nothing to add to Reinke and 

 Berthold's description of these spherical spores. They were 

 produced in considerable numbers in all cultures but not so 

 freely as the conidia. They developed extraordinarily abun- 

 dantly in a sterilised cold water extract of ground Quaker 

 Oats. 



Their walls are thicker than those of the conidia and they 

 are often more or less " warty," although this irregular thickening 

 varies somewhat in different media and is sometimes completely 

 absent. They germinate readily enough, but probably are 

 more resistant to adverse conditions than the conidia and may 

 serve, therefore, as resting spores. No experiments, however, 

 were made on this point. A germinating chlamydospore is 

 illustrated in Fig. ii, Plate IIL 



Development of Perithecia. During the first three or four 

 months that the fungus was cultivated no perithecia were 

 formed on any of the media used. Since they occur naturally 

 on rotting potato tubers, special attention was devoted to 

 culture on these. The fungus was planted on tubers affected 

 with blight {Phytophthora infestans) both sterilised and unsteri- 

 lised, as well as on sterilised tubers affected with "Pink Rot" 

 {P. erythroseptica) . Luxuriant growth developed in all cases 

 but no perithecia were formed, although the cultures were 

 kept under observation for fifteen months. 



During the winter of 1913-14, the detailed culture work was 

 suspended, but the stock culture was kept going by transfers 

 at monthly intervals, mostly on oat extract agar, all the 

 intermediate transfers being kept. After the fungus had been 

 in culture for nearly a year perithecia began to develop both 

 in some of the older transfers, which had been kept, and in the 

 more recent sub-cultures on oat extract agar. 



It would appear, therefore, that the fungus requires a more 

 or less prolonged period of growth under artificial conditions, 

 before it becomes stimulated to produce its perfect form of 

 fructification. Having once reached this stage, the production 

 of perithecia proceeds more rapidly. Thus, from a culture in 

 which perithecia were present sub-cultures were made on 

 sterilised potato stalks and sterilised portions of tubers, and 

 within a month perithecia were developed. They were also 

 formed on oat extract agar, Quaker Oat agar and beer-wort 

 gelatine, but not quite so rapidly. In no case were they formed 



