Howard.—On a Disease of Tradescantia . 35 
Nevertheless, other writers have insisted also on the 
autonomy of the genus Hormodendron , of whom Bruhne 1 is 
especially worth noting, since the form he describes is para¬ 
sitic on Barley with symptoms almost identical with those of 
the present disease. 
Laurent 2 and Costantin 3 both maintain that Hormodendron 
and Cladosporium are merely forms of one and the same 
genus; Janczewsky 4 , on the other hand, failed to obtain 
Hormodendron from Cladosporium or vice versa. 
The whole controversy—in so far as it concerns these two 
genera—really seems to turn on one or two trivial points of 
difference, as already indicated, and of which the following 
are further illustrations. 
Schostakowitsch ( 1 . c. p. 367) says the spores of Hormo¬ 
dendron have smooth surfaces, those of Cladosporium being 
warted: nevertheless Bruhne figures the conidia of his Hormo¬ 
dendron ( 1 . c., Plate I, Fig. 2) with warts, and expressly states 
( 1 . c. pp. 5 and 6 ) that they are smooth or warted according to 
the different conditions of culture. 
Again, Schostakowitsch ( 1 . c., p. 370) says that Cladosporium 
£ besitzt die merkwiirdige Eigenschaft, bei o - 2° C. seinen 
vollen Entwickelungsgang zu durchlaufen . . . Die Hormo- 
dendronsporen vermogen unter solchen Bedingungen nur 
kurze Keimschlauche zu bilden.’ Nevertheless Bruhne ( 1 . c., 
p. 31) shows that cultures of Hormodendron produced spores 
abundantly at temperatures ranging from 5*5° at mid-day to 
‘ einige Grade unter o° C.’ at night, and the vessels were frozen. 
It is obvious, therefore, that much remains to be done 
before we can regard this question as settled. Meanwhile, it 
is interesting to note that the course of events in the life- 
history of this Fungus on Tradescantia , and in the parasitism 
it displays, are extremely similar to those above referred to. 
1 Hormodendron Hordei, Zopf s Beitr. zur Phys. u. Morph, niederer Organismen, 
Heft 4, 1894, p. 1. 
2 Recherches sur le polymorphisme du Cladosporium herbarum, Ann. de 1 ’Inst. 
Pasteur, Vol. ii, 1888. 
3 Sur les variations des Alternaria et des Cladosporium, Rev. gen. deBot., 1889. 
4 Zur Entwickelungsgeschichte von Penicillium, Pringsh. Jahrb., Bd. vii. 
