52 ELEVENTH REPORT. 



gena. The American form as commonly found has smaller conidia than 

 the Euroj^ean form, and the habitat is different in the two countries. While 

 in Europe the species is found generally on Pome fruits, in America it is much 

 more frequently found on stone fruits. 



I am unable to explain the difference between the measurements of asci 

 as given by Norton (1902) and as found by Reade and myself. It is possible 

 of course that there are two species in this country. But Norton's measure- 

 ments are different from those of both Sclerotinia fructigena and Sclerotinia 

 cinerea. The question suggests itself, are there two species occurring in 

 this country and neither of them Sclerotinia cinerea? I am inclined to think 

 there is a mistake in Norton's measurements. Perhaps he measured only 

 the spore bearing part of the ascus, and not the long slender basal part. 

 The view that Norton's figures are wrong is apparenth' taken by Reade to 

 whom Norton sent some material supposedly the same as that from which 

 he described the apothecia. Reade gives the asci as in the table. 



The table of measurements given above shows that the size of the conidia 

 has a wide range of fluctuating variability for both species, while the size of 

 the asci and ascospores is far more constant except Norton's measurements. 

 The measurements of the asci and ascospores is therefore a more satisfactory 

 means of distinguishing these two species, and probably others, than the 

 measurements of conidia. It may be noticed that in the measurements 

 given by the writer in the talkie above, the conidia on agar cultures were 

 smaller than those found on plums in the open. Woronin found that in his 

 artificial cultures he got much larger conidia than in the open. However 

 he used rich organic media while mine contained only mineral salts and agar, 

 and the mycelium on which these conidia develoj^ed grew from ascos]3ores, 

 and not from conidia. The results indicate that the size of the conidia has 

 a very direct relation to the medium or habitat. 



It is worth noting that the ascospores of Sclerotinia fructigena can develop 

 a mycelium on a medium containing no organic material except agar, if the 

 necessary mineral salts are present. The latter used were monopotassium 

 phosphate, magnesium sulphate, and ammonium nitrate. 



Many ascospores germinated on the disc, and a number of them were found 

 with a septum after germination. This septum was located sometimes in 

 the middle of the s))ore and sometimes near one end. Like the mycelium 

 produced from conidia as found by Woronin, the mycelium from the 

 ascospores also produces flask-shaped conidiophores with microconidia. 

 globular bodies 2.5-3 micromillimeters in diameter. In some cases these flask- 

 shaped conidiophores grow almost directly upon the ascospore or crowdetl 

 on a very short germ tube. Dense tufts of these conidiophores bearing 

 conidia are also found on the well develoj^ed mycelium. The two kinds of 

 conidia were found in the same culture. The germination of the ascospore 

 is therefore just like that of the conidia as Woronin found it. Norton did 

 not find the microconidia in his cultures. In the one questionable case he 

 has nothing like the flask-shaped conidiophores in his drawing. 



Saccardo in volume 18 of the Sylloge Fungonim gives a description of 

 Sclerotinia fructicola (Winter)j Rehm, first described by Winter in 1883 

 under the name of Ciboria fructicola, from rotting peach fruits in North 

 America. Winter's measurements of asci and ascospores are all within the 

 limits of those given by Reade for Sclerotinia fructigena (1908) except that 

 Winter gives the width of the ascospores as 4-4.5 while Reade gives them 

 as 5-8 micromillimeters. This difference is too slight to indicate a different 

 species, especially as onl}' one species is recognized on the peach in the U. S. 



