368 Dr. J. O. W. Barratt. [Decay 
red blood cells of the rabbit ranged, in these experiments, between that 
recorded in the sixth column in Table V and that given in Table VI. 
Experiments made with sera of normal mice containing smaller amounts of 
complement did not permit a sufficient range of action and, in consequence, 
were not available for complement deviation tests. 
Table VI.—Hemolytic Action upon Red Blood Cells of Rabbit of active 
Serum obtained from 18 Mice which had previously received Injections 
of Rabbit’s Red Cells. Temperature of experiment, 37° C. 
23 per cent. Heemolysis at the end of— 
No. of suspension of | Active serum of 
tube. red blood cells | inoculated mice. 
of rabbit. | 30 mins. | 90 mins. 
| cic: Cie: 
1 0 02 | 0-001 | Not recognisable | Exceedingly slight 
2 0°02 | 0 0038 3 | Slight 
3 0-02 | 0-009 _ Nearly complete | Complete 
4 0 02 | 0 027 . 53 
5 0:02 | 0-054 “i | iS 
The complement fixation power of the mouse tumour extract was tested 
with normal mouse serum as the source of complement. At first a series of 
observations was made in which varying amounts of tumour extract were 
mixed with a definite amount of normal mouse serum, and after keeping for 
one hour at 37° C. added to sensibilised red blood cells of the rabbit (the 
serum employed for sensibilising the red cells being pipetted off before 
adding the mixture of normal mouse serum and tumour extract). This 
series is given in Table VII. It will be. seen that with normal mouse A 
0-009 cc. of tumour extract fixed the greater part of the complement 
contained in 0°01 ¢.c. of the normal active serum of the mouse. This was 
the usual result, but in the case of some mice, as Bin the same table, the 
tumour extract fixed much less complement. 
A second series of experiments, similar to the preceding but with the 
addition of varying amounts of inactivated normal mouse serum, was now 
made. The results are given in Table VIII. The amount of complement 
contained in 0:01 c.c. of active normal mouse serum was nearly completely 
fixed by 0:01 ¢.c. of mouse tumour extract in the presence of 0:01 ce. of 
inactivated normal serum. This, it will be observed, does not differ markedly 
from the action of mouse tumour extract acting alone, exhibited in 
Table VII. If, however, the two series of experiments are carried out 
simultaneously, the same active mouse serum being employed in both, it is 
