34 Howard .— On a Disease of Tradescantia. 
pricking the upper epidermis. No spores were sown on the 
control leaves. In three days infection took place, the spores 
sending out hyphae which passed down into the leaf. (See 
Fig. 23.) 
As regards the systematic position of this Fungus, we are 
again—since no higher form of fructification could be ob¬ 
tained—driven to regard it as one of the Hyphomycetes or 
Fungi Imperfectly and of the four great groups into which 
these are divided, the present form clearly comes into the 
second one, viz. the Dematieae, characterized by the dark- 
coloured hyphae and conidia, and the absence of any fasci¬ 
culate stipes or 1 sporodochium V 
Now appears a difficulty, however. If we follow the classi¬ 
fication logically, the present Fungus falls naturally into 
section I, Amerosporeae , because the elliptical or oblong 
conidia are continuous, i. e. non-septate; but it is evident 
on comparing it with Cladosporium (which Saccardo puts into 
section II, th z Didy mo spore ae with typically uni-septate spores) 
that our Fungus comes into that or a closely allied genus. 
Adhering to the classificatory scheme of the Sylloge, how¬ 
ever, we place it in the second subsection (. Macronemeae) of 
the Amerosporeae , and so get to the genus Hormodendron. 
A good deal of light is thrown on the matter by a paper 
published by Schostakowitsch in 1895 on the conditions of 
conidia-formation in the Sooty Moulds 2 , where he shows 
pretty clearly that Hormodendron cladosporioides , Sacc., is 
practically Cladosporium , although the author himself attempts 
to uphold the individuality of both. This seems hardly 
possible in view of his own admission, on p. 369, that on 
agar ‘ Cladosporium bildet hier eine Form, die man sehr schwer 
von Hormodendron unterscheiden kann,’ and the comparison 
of his own figures on pp. 366 and 368 points also to the 
practical impossibility of maintaining the autonomy of the 
two genera by characters of any utility. 
1 See Saccardo, Sylloge Fungorum, Vol. iv. 
2 Ueber die Bedingungen der Conidienbildung bei Russthaupilzen, Flora, 
Bd. lxxxi, 1895, p. 362. 
