14 
lese, thus correcting the older view of a capsular wall—was not 
satisfactorily demonstrated. It certainly is not Botryosporium, 
which is the only genus of Hyphomycetes mentioned by Farlow 
and Seymour as occurring on North American plants of Dahlia 
variabilis, Desf. The conidia themselves were carefully studied 
and a few cultnre experiments were made with negative results. — 
The conidia are mediumly thick-walled, hyaline. The cells 
of the central filament, in the infraconidial portion, were, in speci- — 
mens measured, from 10 to 18 y« in diameter, and from 10 to 40# © 
in length. The cell contents in the infraconidial portion were — 
pretty free from granular substances, and were in some cases” 
slightly refringent; but in the conidial portion the cell contents 
became decidedly granular. This granulousness was most marke 
in the terminal area of the central filament, where, too, glycogen 
tests revealed an abundance of this substance. 
Very good diagrammatic representations of Acrostalagmu 
conidia-bearers is given in Fig. 3 on p. 37 of Zopf’s Die Pilze 
but this considers only a simple case where the branching is no 
even secondary, to say nothing of ternary or quaternary. Fig. 3 
Pp. 42, of the same work gives a rather better idea of the mor 
complicated forms, such as have been described above. 
DESCRIPTION OF PLATE CXXIII. 
Figures illustrating the development of conidia-bearers in Acrostalagmus, Cords 
sp. und. All were drawn under Leitz obj. 7, 9 and jy with the Abbe Camera, fro 
specimens cultivated on stems of Dahlia variadilis, Desf, in the plant-house of th 
University of Minnesota, May, 18g1. 
Fig. 1.—Tip of central filament, showing mode of origin of primary brane 
hyphz in whorls of fours. 
Fig. 2.—Young branch-hypha. 
Fig. 3.—Older branch-hypha, showing origin of secondary branch-hyphe. 
Fig. 4.—Still older branch-hypha, showing secondary hyphe more fully deve 
oped and producing the temary lobes. 
Fig. 5.—Conidia, abstricted and showing fusiform or sharply ovate shape. 
Fig. 6.—Branch-hypha, showing developed secondary hyphz and ternary lobe 
some of which are bearing immature conidia. Illustrates also the acropetal suce 
sion of conidia. 
Figs. 7, 8, 9.—The first appearance of the i oaepum sane and the segmentati 
of the primitive bud. 
Fig. 10.—A single conidial lobe showing method of conidial abstrictio 
(Optical section). 
