370 Dr. J. O. W. Barratt. | Dec. 5, 
Table VII I.—Complement Fixation by Mouse Tumour Extract in the Presence 
of Inactivated Normal Mouse Serum. The contents of each tube, after 
standing at 37° C. for one hour, were added to sensibilised red cells 
obtained from 0:02 c.c. of a 24-per-cent. suspension of the red cells of 
the rabbit, and the mixture kept, with occasional shaking, at 37° C. for 
a further period of two hours. 
| | | 
Active |0°85 percent.| Inactivated M Hemolysis at end of — 
: ouse 
No. of serum of solution serum of 
; tumour 
tube. | normal of sodium normal Alec | 
| mouse. | chloride. mouse. . ; 30 mins. | 120 mins. 
Normal Mouse C. 
Ce. Cie: Gis G.C. 
iL 0-00 0-02 — ; o— Slight Marked 
2 0 ‘009 0 02 = — Marked Nearly complete 
3 0 027 0 02 — — Nearly complete Complete 
4 | 0°010 = 0-010 0-003 Slight Slight 
5 | 0-010 uate 0-010 0-009 i if 
6 0-010 — 0-010 0 °027 Very slight Very slight 
ean 0-010 ~- 0-050 0:040 | Not recognisable | Not recognisable 
8 | 0-015 0 -050 0-080 é < 
Normal Mouse D. 
9 0-010 0 045 — ; o— Partial Nearly complete 
10 0 ‘020 0-035 — — 3 et 
11 0 -030 0 025 — — Nearly complete Complete 
12 0-010 0 °022 0-010 0-603 | Exceedingly slight Marked 
13 0 ‘010 0 015 0 ‘010 0 010 53 Slight 
| 14 0-010 — 0 ‘010 0°025 | Not recognisable | Not recognisable 
15 0-020 0-012 0 020 0-003 Partial Nearly complete 
16 0 -020 0 005 0 -020 0:°010 | Not recognisable Slight 
1g, 0 :020 — 0 -020 0 025 55 Not recognisable 
18 0 -030 — 0-050 0-003 Slight Partial 
19 0-030 — 0-050 0°010 | Not recognisable |Exceedingly slight! 
20 0 :030 — 0°050 | 0:°025 ‘ Not recognisable | 
observations is given. As in the experiments described in the preceding 
section, it is again not evident that a stoichiometric relationship exists 
between complement and amboceptor or between amboceptor and antigen. 
In view of the above results it became evident that, in testing the relative 
amount of complement fixation effected by mouse tumour extract in the 
presence of inactivated mouse serum obtained respectively from normal 
mice and from mice with tumours, the most convenient amount of 
inactivated normal mouse serum (having regard to the small scale on which 
these experiments must of necessity be made) would be 0°005 cc. to 
0°01 cc. and that 0°025 cc. of tumour extract would contain much more 
antigen than would be required for the amboceptor (corresponding to the 
antigen) contained in this serum. The amount of inactivated tumour mouse 
