500 
Journal of Agricultural Research 
. Vol. XXVI, No. io 
and i cc. from the second tube is transferred to the third tube, and so on 
until the tenth tube, i cc. from this tube being discarded. This procedure 
gives a dilution of the spinal fluid of from i to io to i to 5,120, the eleventh 
tube being a control on the gold solution. Five cubic centimeters of the 
colloidal gold solution is then added to each tube, the rack shaken and 
left at room temperature, and the reading made in 24 hours. The read- 
S COLORLESS 
0 J 
4 PALE BLUE 
3 BLUE 
2 PURPLE 
/ RED BLUE 
© 
ORED 
■ 
O 
O 
/ 
2 
5 
5 
3 
O 
O 
O 
Flo. 1.—Colloidal gold test of spinal fluid of horse 128. 
ing is made according to the amount of precipitation which takes place 
in each tube and is recorded on a form shown in Figures i to 4. Five on 
the scale, or colorless, represents complete precipitation; 4, 3, 2, and 1 
are varying degrees of precipitation, and o, or red, indicating no change 
of the solution. 
The spinal fluid from horse 128 gave a reaction to the colloidal gold 
test as shown in Figure 1. 
S COLORLESS 
4 PALE BLUE 
3 BLUE 
2 PURPLE 
/ RED BLUE 
ORED 
00 o o o 00000 
Fig. 2.—Colloidal gold test of spinal fluid of blackleg calf No. i. 
Spinal fluids, from three calves, No. i, 2, and 3, dead of artificial 
blackleg infection, were used as negative controls. The testing of a 
number of spinal fluids from such blackleg infected animals usually 
results in 10 naughts. In a few cases, however, a No. 1 change on the 
scale in several of the tubes was noted. The results are shown in figures 
2, 3, and 4. No spinal fluid from a normal equine was available for 
control purposes. 
