JULY 30, 1897.] 
all over with small crystals. It is easy to 
prove that this deposit is sulphur, since the 
granules can be dissolved away in carbon 
bi-sulphide, leaving only the gelatinous 
filament quite soft and flaccid, where it was 
formerly somewhat stiff and stringy. One 
sees no further indication of organization 
until the filament is examined under an 
immersion lens with, perhaps, a magnifica- 
tion of 1,000 diameters. Even then, to ob- 
tain the best results, the specimens must be 
Such preparations then reveal 
The filament is 
stained. 
a remarkable structure. 
SCIENCE. 
149 
ment is really an elongated zoogloea, or col- 
ony of bacteria, all coated over with sul- 
phur grains. 
It is a difficult matter to determine ex- 
actly what form of the bacteria this is. One 
should know whether the sulphur grains 
are deposited by the activity of the organ- 
ism or not. Presumably this is so, and the 
type is a species of Beggiatoa, a genus of 
bacteria characterized by its peculiar habit 
of depositing sulphur from water contain- 
ing sulphuretted hydrogen in solution. But 
the genus Beggiatoa is remarkable because 
GSA 
el EO» 
si a = 
ae PR Ry 
oem d 
Fig. 4. 
made up of innumerable bacteria imbedded 
in a gelatinous matrix. They are chiefly 
rod-like forms and are arranged in lines 
and chains. The individual rods vary 
greatly in length, but it is quite plain that 
the smaller forms result from the division 
of the larger. Fig. 4—a illustrates the char- 
acteristic form and arrangement of these 
bacteria under very high magnification, 
about 2,000 diameters. The long axis of 
the rods are usually parallel with the gen- 
eral direction of the filament, the width of 
which is made up of many hundreds of the 
organisms placed side by side. The fila- 
it includes some of the largest species of 
bacteria known, and the cells are of such a 
size that many sulphur grains may be con- 
tained in their interior. There are without 
question species of Beggiatoa in the hot 
springs of the Park, and it may be just as 
well to compare one of these forms shown in 
Fig. 4—b, under magnification of 500 diam- 
eters, with the organism under consider- 
ation. It will be seen that the cells of the 
Beggiatoa filament are very large in com- 
parison with those of Fig. 4-a, although 
the magnification of the latter is about 2,000 
diameters. The’ dark dots in the interior 
