610 MINNESOTA BOTANICAL STUDIES. 
Method of collection.—The method of collection is practically 
the one suggested by Dr. Smith Ely Jelliffe * and is as follows: 
A piece of absorbent cotton four or five inches square and one 
inch thick is attached by means of a twelve-inch square of un- 
bleached muslin to the water faucet. The water is then turned 
on sufficiently to insure a constant stream and is allowed to run 
from ten to twelve hours, after which the cotton is removed. 
The cotton, which is usually quite brown from the organisms, 
is divided into pieces and rubbed and rinsed in five beakers each 
containing 200 c.c. of water. The water is then poured into 
one vessel and allowed to settle, after which the deposit is put 
into a glass containing 25 c.c. A few drops of this is trans- 
ferred to a slide by means of a pipette and examined microscop- 
ically. At least ten mounts from each week’s collection of ma- 
terial was examined in this way. ‘The rest was then preserved 
in 2 per cent. formaline for future reference. 
For the records, Dr. Jelliffe’s method of computation was 
adopted. In computing the numbers the following schedule 
was used : 
Abundant, 25 + in one c.c. of water. 
Common, 10-25 in one c.c. of water. 
Few, 5-10 in one c.c. of water. 
Scarce, I-5 in one c.c. of water. 
Present, Less than five in one c.c. of water. 
Since November, 1899, weekly collections have been made of 
the plant life in the St. Paul water supply and the organisms 
identified (as far as possible) and their number computed. 
The vegetable organisms found were all alge if we except 
the pollen grains and Fungi spores that appeared occasionally. 
The Algee found were as follows: 
1. Diatomaceea, 13 varieties. 
Cyanophycee, 11 varieties. 
3. Chlorophycea, 32 varieties. 
4. Peridinie, 2 varieties. 
to 
Of these some forms of Diatoms were present almost con- 
stantly, especially Jelosira, Stephanodiscus, two varieties of 
*Jelliffe, S. E. A preliminary report upon the microscopical organisms found 
in the Brooklyn water supply. Brooklyn Med. Journ. 7: 595. O. 1893. 
