2G LORANDE LOSS WOODRUFF 
straining it through cheese cloth. This eliminated all but an 
insignificant number of the smallest fragments. 
C Infusions. To make up this set, 20 grams of hay was put 
into five liters of tap water. It was neither boiled nor strained. 
A few drops of ‘seed’ was added, thus insuring the presence of all 
the chief forms seeded into the A and B infusions. 
The twenty-six infusions were made up at intervals and were 
designated as follows: 
April 1st: A-1, A-2, A-3, A-4, A-5, A-6, B-1, B-2, C-1, C-2, and C-3. 
April 13th: A-21, A-22, B-21, and B-22. 
April 24th: A-31, A-32, B-31, B-32, and C-31. 
May ist: A-41, A-42, B-41, B-42, C-41, and C-42. 
Hach of the infusions existing during April was studied daily 
from its inception to May Ist. After this date the observations 
were made for a while at forty-eight hour intervals, and then at 
somewhat longer intervals depending on the rapidity of change 
in the respective cultures. The last regular count was made on 
June 26th, 1909, but since that time up to the present (Oct., 1911) 
the infusions have been kept under general observation. 
The methods of study consisted of an examination of samples 
of the liquid taken from the top, middle and bottom of the jars, 
and the enumeration of the different Protozoa, Rotifera, Algae, 
etc., which were present. The liquid was removed from the 
jar for study with a 5 ce. pipet. The ‘surface’ medium studied 
was taken from three points in the jar just under the surface film; 
one at the side nearest to the chief source of light, another at the 
side farthest from the chief source of light, and the third 
directly at the centre of the surface of the infusion. The ‘middle’ 
medium was taken from this portion of the infusion by inserting 
the point of the pipet quickly to the region, while the other end 
of the pipet was closed with the finger. The ‘bottom’ medium 
was taken in a similar manner. In ‘middle’ and ‘bottom’ counts 
care was exercised to move the tip of the pipet through the re- 
spective regions in order to get a representative sample. Only one 
pipetful was taken in each of these counts because of the possi- 
bility that a few organisms might get into the pipet when it was 
passing through the upper portion of the fluid on its downward 
