162 Prof. D. A. Welsh and Dr. H. G. Chapman. [Dec. 17, 
during the experiment. After 48 hours the clear superfluids were removed, — 
and were usually subjected to further experiment, either by addition of more 
homologous protein, or by addition of fresh antiserum from another immunised 
animal. Since it had been shown* that different homologous antisera might 
interact to yield a precipitate, appropriate controls were carried out which 
showed that no trace of deposit occurred as the result of the interactions 
with one another of the antisera used in these experiments. 
The deposits from the interactions were shaken up three times with 50 c.c. 
saline solution, and separated by the centrifuge. They were then washed five 
times with 50 c.c. distilled water, whereupon the superfluid yielded no trace 
of soluble protein. After three washings with absolute ethyl alcohol, they 
were finally treated with ether free from water. On removal of the excess 
of ether with a pipette, the deposits were placed in an oven at 50° C. for 
24 hours, and dried to constant weight in a desiccator over calcium chloride. 
The weighings were made in small glass test-tubes of about 7 grammes tare, 
in which the final washings with alcohol and with ether had been carried 
out. 
Amount of Precipitum obtainable from Large Quantities of Antiserum with 
Small Amounts of Homologous Protein. 
Five experiments were undertaken, and the results are summarised in 
Table I. 
Table I. 
| : 
lino. Weight 
: : of 
ee. Weight of homologous protein Amount of antiserum (fresh). precipi- 
| experi- | (dried). | Pepa 
| ment. | (dried) 
\ | 
milli- 
| | grammes. 
(eral | 2°5 milligrammes hen egg-white...... 19 c.c. hen egg antiserum (No. 40) ...,; 18:0 
2 | 2°5 milligrammes hen egg-white...... 20 c.c. hen egg antiserum (No. 41) ...| 18:0 
3 (a) | 1:0 milligramme horse serum......... 19 c.c. horse antiserum (No. 43) ...... 2°2 
3 (6) | Supertiuidot 3 (a) si. .ci...- 2.4.2 .s508s 18 c.c. horse antiserum (No. 42) ...... 5°0 
4 (a) 1:0 milligramme ostrich egg-white...| 20 ¢.c. ostrich egg antiserum (No. 44) 5 °0 
4 (b) | 40 milligrammes ostrich egg-white | Superfluid of 4 (@) .....c.cseeeeesee eens 11 °0 
5 (a) | 1:0 milligramme hen egg-white ...... 18 c.c. hen egg antiserum (No. 47) ...) 13:0 
bu) a Supertiuid Of O00) Bes. .scte.scsscees 16 c.c. hen egg antiserum (No. 46) ... 8 °5 
5 (c) | Superfluid of 5 (6) .t.......00..c0steses 18 c.c. hen egg antiserum (No. 48) ... 4 *4, 
In experiment (1) 2°5 milligrammes dried hen egg-white interacted once with 
19 ee. fresh hen egg antiserum (No. 40) and caused the formation of a deposit 
* Nuttall, Hopkins, and Strangeways, quoted by Nuttall, ‘Blood Immunity and Blood — 
Relationship,’ p. 129, Cambridge, 1904. 
