140 A Monograph of the Ervsiphaceae 



and the occurrence of the fungus on the " erineum," as we find a 

 form of M. alni with uncolored appendages, but otherwise cer- 

 tainly indistinguishable, on the leaves of the same host-plant when 



no galls are present. 



On the other hand, the coloring-matter appears in the ap- 

 pendages of M. alni on other hosts without the occurrence of 

 ealls. This is well seen in the curious form of M. alni on Corylns 

 rostrata^ var. MandsIiHrica (more fully referred to later on), and 

 also in a verj^ interesting specimen (now in the Kew Herbarium) 

 sent to me by Professor Galloway from the Herbarium of the U- 

 S. Dept, of Agriculture. This specimen was labelled ''M, semitosta 

 B. and C. on Ccphalantliits occidnitalis Needham, Indiana. E. M. 

 Fisher, September, 1890, No. 11 54/' The material consists of 

 four leaves; three of these have traces of ** erineum*' on them, 

 while the fourth is quite free. On all the leaves, how^ever, the 

 perithecia have appendages which are colored throughout, exactly 

 as In *'J/ erineophila^' with w^hich the fungus often agrees in all 

 characters. On the three leaves where galls are present, the 

 perithecia, unlike those of ''M, erincopliila'" on Fagus fcrntginea 

 are scattered over the surface, and occur only rarely, probably 

 only accidentally, on the galls. Sometimes the appendages are ^ 

 longer (twice the diameter of the perithecium), and the apical 

 branching shows signs of becoming more widely forked, when we 

 are reminded of the form on Corylus restrain, var. Mandshiirka. 



In conclusion it is seen from the above remarks that we have 

 in the series of forms of M, alni ones that show a colored base to 

 the appendages, others in which the appendages are colored half 

 way [^'M. seniitosta''\ and finally those in which the color reaches 

 to the commencement of the apical branching {^'M, crincoplula^ 

 and certain forms on Corylus rostrata, var. MandsJiurica, and Ccpha- 

 lanthus occidentalism I feel convinced, therefore, that in M. alni the 

 absence or presence of color in the appendages must be regarded 

 as a character of no systematic value. 



Nor can we regard M. erincophila as a '* biological species 

 dependent on the gall (as is perhaps the case with Sphaerothcca 

 phytoptophld)^ since we find the same form occurring on leav^es of 

 Cephalanthus occidentalis free from the ''erineum." 



M. aba occurs apparently only very rarely on the host^ plant 



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