H. WORMALD 181 



American form is very unlike that of M. fructigena and the conidia too 



are smaller than in the latter as will be seen by comparing the dimensions 



given below with those of M. fructigena. 



The dimensions of the conidia of those strains where 100 conidia 



were measured were as follows : 



Average of 100 conidia 



Strain C, mummied peach from Ontario 

 ., D „ plum ,, „ 



„ E, culture (peach) from Wisconsin 

 ,. F, mummied plum ,, „ 



„ G,ascosporicculture(peach)fromOntario 

 „ H „ „ (plum) „ 



The most uniform results are obtained on prune- juice agar but as 

 all the British strains do not develop conidia^ under those conditions 

 a comparison of the size of the conidia of the various forms from this 

 culture medium cannot be made. 



Growth is vigorous on the media employed; in one case conidia 

 placed on agar germinated at room temperature (about 18° C.) producing 

 within three days sporelings 3 mm. in diameter, and already short chains 

 of conidia were present. On prune- juice agar plates growth takes place 

 at a more rapid rate than in the case of the grey Monilias of this country, 

 and the periodicity in rate of growth observed in the latter is absent from 

 the American form which grows out uniformly from the point of inocula- 

 tion to the edge of the plate. 



In a paper recently published Bartram{5), working with strains of 

 Monilia obtained in Vermont, concludes that the form in that state is 

 M. cinerea but finds that it produces conidia in agar cultures ; it is 

 probable therefore that the Vermont strains resemble those received at 

 Wye from Oregon, Wisconsin, and Ontario and that that form is the 

 one commonly found in North America. 



{d) Continental Strains of Monilia. 



From our geographical situation and the frequency with which 

 nursery stock is imported from the Continent it is natural to expect 

 that the Monilias of this country would be closely related to, if not 

 identical with, those of the rest of Europe, and from descriptions 



^ Very rarely have I seen an occasional short chain of conidia on plate cultures of 

 M. fructigena on this medium, but no definite pustules or tufts of conidiophores have 

 developed, nor sufficient conidia for comparative measurements. 



