52 
when stained with polychrome methylene blue, such as Goldhorn’s. 
We call atention to this, for isolated yeast bodies of this character 
stained thus might lead to errors of interpretation. 
THE BLOOD IN YELLOW EEVER. 
We are fully justified in concluding that in the blood of yellow- 
fever cases there is a living entity floating free in the plasma and 
capable of reproducing the disease. The positive results obtained in 
the filtration and inoculation experiments done by Reed and Carroll, 
corroborated by the French commission and ourselves, is sufficient 
proof of that statement. 
We carefully examined many blood smears stained with poly¬ 
chrome methylene blue of Wright and Goldhorn, and failed to see the 
presence of any body which could be considered to stand in any causal 
relation to the disease. 
The smears were taken from IT cases at periods of five hours to six 
days after the onset of the disease. In every case blood was taken 
within the first three days of sickness. In several cases the blood was 
taken daily or on alternate days. The corpuscles and plasma were 
carefully searched. The red cells often showed minute blue bodies, 
usually round and sometimes slightly irregular, which resemble those 
ascribed to cell degeneration or nuclear rests in anemia. 
The mononuclear leucocytes and polymorphonuclear neutrophiles 
often showed in their protoplasm small, round, clear spaces having a 
punched-out appearance. These spaces could not be made to take up 
any one of several stains employed. They were also found in mala¬ 
rial and normal blood. 
In making our blood preparations we used a method devised by one 
of us (Rosenau) about four years ago, w T hich has been in constant use 
in the Hygienic Laboratory since, and as it has proven so satisfactory 
in our hands we will describe it. The technique was suggested by the 
glass slides commonly used for this purpose. The instrument consists 
of a little glass apparatus we call the “ spreader,*’ made by simply 
welding two pieces of solid glass rods together, as shown in fig. 1. 
The short arm should be true, so as to lie flat when applied to the 
slide, and should be several millimeters shorter than the width of the 
slide. A drop of blood is taken from the ear or finger tip and placed 
upon one end of the slide in the usual manner. The spreader is then 
applied to the drop, and if the glass is clean the blood will at once be 
drawn by capillary attraction across its whole length; it is then 
spread by a gentle, even stroke, without undue pressure, along the 
