84 
1 c. c. The observations on the qualit}^ of the test dose follow in the 
succeeding paragraphs/* 
7. The test poisons are, when liquid, to be examined at least once a 
month upon culture media for. sterility. 
8. The test dose of poison is to be redetermined every six weeks by 
means of the test dose of serum in such a way that both the test dose 
of the poison and its neutralizing point may be determined anew. If 
in these redeterminations a considerable weakening of the test dose 
develops, then the poison must be considered as being in dissolution 
and should be replaced b}^ a new one. 
9. The attention of manufacturers must be brought to the fact that 
the test poison in small quantities is very apt to decompose; particu- 
larly a very short exposure to light will cause an appreciable weaken- 
ing. It'is therefore recommended that they obtain every three weeks 
a new poison from the Institut. 
^According to my observations, to carry out the test with exactness it is not nec- 
essary for the test dose to contain a maximum amount of poisonous affinities. From 
the viewpoint of technique, old weakened poisons preserved with toluol are pre- 
ferred, because after the weakening has taken place they will preserve their value 
for years. 
