Macrosporhim parasiticttm , - Thiim . 1 5 
accompanying a stronger parasite, as Peronospora Schleideniana , 
or by attacking a plant on its less active tissue, as the sheath of 
the onion-plant. A statement was however made by De Bary 1 
on the possibility of species of Pleospora being classed among 
facultative parasites. In fact, observations in regard to the 
parasitic nature of Pleospora herbarum are not wanting. 
Spegazzini 2 has found this fungus on the living leaves of 
grape-vine and Medicago sativa\ Cugini 3 and Passerini 4 on 
living branches of mulberry-trees ; Berlese 5 , on branches of 
Sambucus nigra ; and Linde 6 , on roots of clover. These 
observations however few in number, supported by our own 
cases on onion-plants, give us sufficient ground to consider 
Pleospora herbarum as a facultative parasite. 
It is now convenient to briefly state some of the main 
points we have arrived at so far. It has been proved that 
the ascosporous stage of Macrosporium parasiticum of Thiimen 
is the common Pleospora herbarum , and that the so-called 
M. parasiticum itself is nothing more than M. Sarcinula of 
Berkeley growing on onion-plants. 
One seldom meets with a plant whose life-history has been 
beset with so much confusion, and about which so many con- 
troversies have been left unsettled for a long time, as Pleospora 
herbarum , the plant we have just been considering. The first 
important work on the subject was by Tulasne in 1863 7 . He 
found in this plant a remarkable illustration of his theory of 
pleomorphism. He included under the name of Pleospora 
herbarum a perithecial, a pycnidial, and four conidial forms. 
Among the latter he distinguished, 1st, the conidia dematiea , 
1 De Bary, Vergl. Morphol. u. Biol. d. Pilze, p. 409, Leipzig, 1884; Eng. trans. 
p. 380- 
2 C. Spegazzini, Ampelomiceti italici: Funghi parassiti al grappolo, p.726, 
1878. 
3 G. Cugini, Intorno ad alcune malattie comparse nel 1884 su varie piante 
coltivate, in L’Agricoltura italiana; an x. Firenze, 1884, Nos. 120, 121. 
4* 4 G. Passerini, Ancora della nebbia o nuova malattia dei gelsi e di alcuni altri 
alberi, in Bolletino d. Comizio agrar. parmense, Parma, 1884. 
5 Berlese, 1. c. p. 99. 
6 S. Linde, Ueber Kleemiidigkeit des Bodens. Leipzig, 1880. 
7 Tulasne, 1. c. 
