324 
The number of bacteria in the water in the 
tank varied largely with the temperature, 
rising in September to 9,000,000, and falling 
in colder weather to a little overa hundred 
thousand in March. The filter bed was, 
therefore, extremely efficient in removing 
bacteria. In the study of the species of 
bacteria found in the effluent, some of the 
common sewage types were found. The 
author found, also, in this effluent, Bacillus 
prodigiosus. This was interesting inas- 
much as it made its appearance in the sew- 
age after it had been introduced into the 
laboratory in Ames. It was not. believed, 
however, to be a native of the locality, but 
an introduced species. : 
Variations of Bacillus rosaceous metalloides 
(Dowdeswell) : Nertson G. Davis, Lewis- 
burg, Pa. Z 
During the summer of 1896 a series of 
experiments was begun on the variations 
of Bacillus rosaceous metalloides. In mak- 
ing a pure culture of the organism, it was 
noticed that one colony was much paler in 
color than the others. No pigment ap- 
peared until the colony was some days old. 
Replating from this colony, all the daugh- 
ter colonies were colorless until the fourth 
day, when a pale pink pigment appeared. 
After a time the characteristic metallic lus- 
ter became visible. A continuation of the 
replating and selection of colonies was kept 
up for ninemonths. By that time cultures 
of the Bacillus rosaceous varying in color 
from colorless to a deep red, deeper than 
the original variety had been obtained. The 
darkest variety of all appeared asa ‘sport’ ; 
so did also the first pale colony. The 
other variations appeared as gradual modi- 
fications. An attempt was made to pro- 
duce a variety that would not liquefy in 
gelatin. This was unsuccessful, although 
in two instances the colonies were ob- 
tained, much slower than usual in their 
action. Similar selection experiments dem- 
SCIENCE. 
[N. S. Von. XIII. No. 322. 
onstrated great varieties in the size of 
the organism. After about two hundred 
replatings, there appeared in one of the 
gelatin plates a colony in which the length 
of the elements was the same as the 
breadth. In other words, it appeared to be 
a coccus 0.5 in diameter, and was so de- 
scribed by students. This variety was cul- 
tivated in various media, at various tem- 
peratures, in light and darkness. It re- 
mained constant in size. 
Some Varieties of Bacillus pyocyaneous found 
inthe Throat: F. P. GoruAm, Providence, 
R. 1. 
Bacillus pyocyaneous isa comparatively fre- 
quent form in the nose and throat. Two 
varieties can be distinguished, one produc- 
ing both pyocyanin and a fluorescent pig- 
ment, the other producing only pyocyanin. 
These forms are often present in almost 
pure culture, and may persist in the same 
individual for several months. The cultures 
are virulent for guinea-pigs and rabbits. 
Demonstration of Photogenic Bacteria: F. P. 
GorHAM. 
Cultures of several varieties of phosphor- 
escent bacteria were exhibited at the even- 
ing session. They were growing on fish, 
fish-agar and fish-bouillon. Some of the cul- 
tures were remarkably luminous. 
Bacillus Lactis Viscosus, a Cause of Ropiness in 
Milk and Cream: ArcuIBALD R. WARD, 
Ithaca, N. Y. 
The writer has closely observed the occur- 
rence of the milk fault, known as ‘ropy 
milk,’ in the creameries of three different 
milk dealers in widely separated localities 
in New York State. Bacillus lactis viscosus— 
Adametz, has been found to be the cause of 
trouble in each outbreak. The identifica- 
tion of the organism found in the ropy milk 
was confirmed by Dr. Adametz, who studied 
a culture sent for identification, and pro- 
nounced it identical with the one first de- 
