416 BOTANICAL GAZETTE [NOVEMBER 
in the plants infected by these spores. Dr1ETEL‘ has already shown that the 
production of “conidia” by the promycelium does not indicate a functional 
differentiation of the teleutospores, but is dependent on external conditions. 
In this matter KLEBAHN agrees with DIeTeL, but the two investigators differ 
somewhat as to the factors which determine the segmentation of the germ 
tubes. KLEBAHN finds that spores germinating within a liquid medium pro- 
duce, in place of normal mycelia, germ tubes which may become segmented or 
not. The number of segments produced is always four, and under some condi- 
tions the “‘conidia”’ produce sporidia. ‘Teleutospores germinating in contact 
with air always produce promycelia and sporidia. Dreret attributes the 
aaa of segmented germ tubes to a scanty moisture supply in the sub- 
f 
son. rdi 
leaves should have contained mycoplasma pick should later have given rise 
to a general outbreak of rust on the leaves. KLEBAHN found, however, as 
the leaves from which the sori had been removed remained free from infectio 
The mycoplasma theory is attacked from another standpoint by Hae 
BEssEL, who finds in and about mature rust pustules of secondary origin on 
leaves of Althaea rosea attacked by mallow rust mycelial structures resembling 
the promycelium described by Ertksson. These structures on account of 
their delicate walls have the appearance of naked masses of protoplasm which 
conform to the shape of the intercellular spaces which they occupy. A study 
of their origin shows that they are the outgrowths of older hyphae at the base 
of the rust pustules. The author attributes to them the function of distributing 
the mycelium through the leaf. Since these structures, conforming in every 
way to ErIksson’s promycelia, are observed originating from the mycelium 
of mature pustules of undoubted secondary origin, the author argues that the 
similar structures of ErRIkssoNn may be explained without the aid of the myco- 
plasma theory. To this conclusion ErIksson would object, as to the other 
similar arguments, that the mycoplasma does not occur in connection with 
rust infections — from spores. Thus the elusive mycoplasma again 
escapes annihila 
A eat oo 8 supplemented by field observations has enabled OLIVE‘ 
to explain some apparently anomalous phenomena in the sequence of spore 
forms and the formation of aecidia in certain rusts with perennial mycelia. 
4 Rev. Bor. Gaz. 56:163. 1913. 
5 HaasE-BEssEL, G., Zur Erikssonchen Mycoplasmatheorie. Ber. Deutsch. Bot. 
Gesells. 32: 393-403. . g. 1914. 
6 OxivE, E. W., Intermingling of ; phytic g 
tions in Puccini Ado £ obtegens, and Uromyces passes Ann. Mycol. 
11:298-311. pl, 
