66 BOTANICAL GAZETTE [yuLy 
Already, by microscopic examination, it had been ascertained that 
in many regions of the central parenchyma of the stem the cells and 
the intercellular spaces enclosed masses of a small ovoid yeast, measur: 
ing from 1.5 to 2.54 on an average. It was, moreover, the only 
microorganism which could be directly observed, even with great mag: 
nification and with the aid of staining reagents. 
It was easy to isolate this yeast in a pure state by taking up the 
germs with a sterilized needle from the center of the stem, the section 
being made with a flamed scalpel, or by removing small cylinders of 
the red tissue from the pith by means of a sterilized trocar. The first 
culture liquid was a 5 per cent. glucose bouillon. Some subsequent 
isolations by means of Petri dishes with bouillon sugar gelatin have 
given, to the exclusion of all other organisms, white colonies formed 
by a yeast morphologically identical with that which had been observed 
in the diseased sorghum. 
Cultivated on the surface of carrot, potato, and on different gelatin 
in the tissues of the plant. Sown in unfermented grape juice, 0 in 
various artificially sweetened liquids suitable for the culture of yeast 
this organism shows a feeble alcoholic fermentation. ‘I'he fermenting 
power is slightly increased by a series of re-sowings in the samé 
medium. My attempts to obtain ascospores have been fruitless, and I 
am not able at present to classify this yeast with the true Saccharo- 
iyces, 
The mere fact of isolating a yeast from the tissues of the blighted 
sorghum i is not sufficient to enable one to conclude that this yeast isa 
parasite, and that it brings about the symptoms of the disease. It is 
known, in fact, that a large number of these ferments may be encoll 
tered on the surface of stems and leaves; it would not be astonishing. 
therefore, if some dead tissues, still containing in their cells a part 
their reserve sugar, were invaded by the saprophytic development ‘ oft 
superficial yeast. The following experiments, however, show that had 
tissues of the plant, and in them brings about the phenomena of the 
blight. . 
Sorghum plants raised from seed and cultivated in a hothouse que 
ing the months of November and December 1898 and January 1899 
were inoculated with pure cultures. All aseptic precautions were 
