12 BULLETIN 395, U. S. DEPARTMENT OF AGRICULTURE. 
fungus with Cladosporium carpopMlum Thum. from peach fruit from 
America, he found only minor morphological differences, but obtained 
inconclusive results from cross-inoculation experiments. Though 
he does not formally conclude that these organisms are specifically 
identical, he expresses the personal conviction (1901, p. 657) that they 
are "ein und denselben Pilz" and calls attention to the fact that 
Pammel (1895, p. 207) and Selby (1897, p. 118) considered Clado- 
sporiums associated with cherry and plum scab in America .to be 
Cladosporium carpopMlum Thum. If Aderhold were correct in his 
belief, it would follow that Cladosporium carpopMlum Thtim. should 
become a synonym of Cladosporium cerasi (Kbh.) Aderh., which in 
turn the same investigator (1900, p. 544) considers to be the im- 
perfect stage of Venturia cerasi Aderh. The data which have been 
presented, however, fail to convince the writer that the organisms 
in question are identical. Therefore, until further evidence is 
adduced, he accepts the name Cladosporium carpopMlum Tniim. 
for the peach-scab parasite. 
While the contributions which have been made to the knowledge 
of Cladosporium carpopMlum since Von Thiimen's (1879) description 
make desirable certain further emendations, it is the belief of the 
writer that, in order to avoid unnecessary taxonomic complications, 
these should not be made until the relationships of the Cladosporiums 
on the stone fruits have been further determined. Meanwhile, Von 
Thiimen's (1879, p. 13) description, which is quoted below, is in most 
essentials clear-cut and accurate. 
CI. maculas orbiculares, saepe confluentes, viridi-nigricantes, annulatas formans; 
hyphis brevibus, erectis, flexuosulis, continuis vel interdum septatis, subramosis, 
tenuibus, 4 mm. crassis, fuscis; sporis fusoideo-ovatis, utrinque obtusiusculis vel raro 
vertice subacutatis, rectis, non vel obscure uniseptatis, diaphanis, 20 mm. long., 5-6 
mm. crass., dilute fuscescentibus. — Thiimen. 1. c. emend. 
In Persicae vulgaris Mill, fructibus maturis, epidemice. — Austria inferior (Thiimen). 
MORPHOLOGY. 
Mycelium. — The morphological characters of the mycelium vary 
much with conditions. The very young hyphse are delicate, hyaline, 
branched, and septate. As the fungus develops, however, the 
diameter of individual cells normally increases, transverse and, more 
rarely, longitudinal divisions occur, and the walls of the more ex- 
posed cells thicken and become olivaceous. On the fruit lesions this 
growth may give rise to pseudoparenchymatous fungal masses, while 
a like development may occur beneath the cuticle of the twigs (figs. 
2 and 4). In culture, stromateoid masses develop (PL III, fig. 3), 
the individual cells becoming much enlarged and often rounded, 
giving an irregularly monihform appearance to the mycelial threads. 
In old cultures the mycelium tends to break up into its component 
cells, which under favorable conditions are capable of putting out 
vigorous hyphse. In all of these stromateoid structures the walls of 
