§ 33-1 
LIFE-TESTS. 
43 
TABLE SHOWING THE RESULTS OF EXPERIMENTS ON FISH. 
No. of 
Experiments. 
Metal. 
Limit of 
Toxicity. 
20 
Mercury .... 
•00029 
7 
Copper .... 
•0033 
20 
Zinc ..... 
•0084 
10 
Iron ..... 
•014 
7 
Cadmium .... 
•017 
6 
Ammonium 
•064 
7 
Potassium 
•10 
10 
Nickel .... 
•126 
9 
Cobalt .... 
•126 
11 
Lithium .... 
•3 
20 
Manganese 
•30 
6 
Barium .... 
•78 
4 
Magnesium 
1-5 
20 
Strontium 
2-2 
5 
Calcium .... 
2-4 
6 
Sodium .... 
$4-17 
V.—Life-Tests : The Action of Poisons on the Lower 
Forms of Life. 
§ 33. The progress of synthetic chemistry places annually a large 
number of more or less toxic substances in commerce, and it may often 
be necessary to ascertain whether a given extract is poisonous at all, and 
if so, what is its action. Similarly, the action of poison on life forms 
generally will assist the toxicological chemist in the identification of a 
substance. 
The chief methods of experiment are the following :— 
1. Action on the red blood corpuscles. 
2. Action on unicellular organisms. 
3. Cephalopoda. 
4. Insects. 
5. Effect of poisons on the heart of cold-blooded animals. 
1. Action on the Red Blood Corpuscles (Erythrocytes). —Any blood 
may be used, but Heinz 1 has proposed that rabbit’s blood should be 
taken as a standard. 
The blood is defibrinated and several test tubes are charged, each with 
10 drops of the defibrinated blood. A solution of the substance in 
various strengths is now added to the blood, adding also common salt to 
each solution so as to bring the concentration equal to 0-9 per cent of 
common salt ; such a solution, with regard to rabbit’s blood, is osmotic. 
1 Handbuch der experimentelle Pathologie u. PharmaJcologie, Jena, 1904. 
