Aug. is, 1914 
Head Smut of Sorghum and Maize 
34i 
in this group this classification seems proper in view of his illustration 
(pi. 30, fig. 37) and of our Plate XXXIII. From these it is evident that 
the spores, as they occur aggregated into irregular groups, are so formed in 
the sorus, for the spore balls are found before the spores are mature or 
even before the latter are differentiated—i. e., while the fungus is still 
in the hyphal stage. 1 
GROWTH IN ARTIFICIAL, CULTURES 
The recent work of Appel and Riehm (1911, p. 346, pi. 4 2 ) has again 
emphasized the fact, first established by Brefeld, that the smuts can be 
cultivated on artificial media in their saprophytic stages. Similar work 
with this organism has been found difficult on account of trouble in 
collecting spore material free from contamination and thoroughly germin- 
able. Indeed, the writer has rarely succeeded in getting over 15 per 
cent of the spores to germinate. The large, open sorus, moist with the 
saccharin juices of the host, gathers yeasts, molds, and bacteria, which 
are very troublesome, particularly in liquid cultures. These were 
attempted repeatedly in several different seasons and at various times of 
the year, but with only slight and irregular germinations, no matter 
what the age, source, or condition of the spores. Cane-sugar solutions 
were largely used, as well as distilled water, rain water, tap water, soil 
decoctions, sorghum sap, beef bouillon, decoctions of carrots and of 
prunes, Uschinsky's solution, and Cohn's solution, the last named being 
also tried in the modified form used by Hitchcock and Norton (1896, 
p. 200) in their work with this smut. The temperatures were not 
controlled or recorded in most cases. 
With solid media, however, the isolation of the spores found germinat¬ 
ing was accomplished by transplanting them with glass hairs under the 
binocular microscope to sterile poured plates, where their development 
into conidial colonies was watched under the microscope. Plates seeded 
thinly enough to contain few contaminations would so seldom show any 
germinating spores that transplanting from a thickly seeded plate proved 
to be the only practicable method of isolating, since the head-smut 
colonies developed so slowly at ordinary temperatures (over a week was 
required after germination for the colony to become visible to the naked 
eye) that the plates would be obscured by other organisms long before 
the smut could be isolated in the usual way. Moreover, the method 
employed made it certain that the conidia thus obtained in pure culture 
were not those of some contaminating yeast. It should be said, how¬ 
ever, that since this was done it has been found that the yeast and bac- 
1 The character of the sorus, particularly in the decided deformity of the whole inflorescence, also seems 
more closely similar to several of the species of Sorosporium than to any of Sphacelotheca as described by 
Clinton (1904, p. 383-395). Although the observations here presented do not appear to be in accord with 
the classification given this form in Clinton’s monograph, the writer is much indebted to Dr. Clinton for 
helpful criticism. 
“Erroneously marked 14 plate 3.” 
