Cnar. XI. GENERAL SUMMARY. 273 
sponding salts of potassium produced no effect, two 
causing slight inflection. Small doses, moreover, of 
some of the latter salts were poisonous. ‘The salts 
of sodium and potassium, when injected into the veins 
of animals, likewise differ widely in their action. The 
so-called earthy salts produce hardly any effect on 
Drosera. On the other hand, most of the metallic 
salts cause rapid and strong inflection, and are highly 
poisonous; but there are some odd exceptions to this 
rule; thus chloride of lead and zinc, as well as two 
salts of barium, did not cause inflection, and were not 
poisonous. 
Most of the acids which were tried, though much 
diluted (one part to 437 of water), and given in small 
doses, acted powerfully on Drosera ; nineteen, out of the 
twenty-four, causing the tentacles to be more or less 
inflected. Most of them, even the organic acids, are 
poisonous, often highly so; and this is remarkable, as 
the juices of so many plants contain acids. Benzoic 
acid, which is innocuous to animals, seems to be as 
poisonous to Drosera as hydrocyanic. On the other 
hand, hydrochloric acid is not poisonous either to 
animals or to Drosera, and induces only a moderate 
amount of inflection. Many acids excite the glands to 
secrete an extraordinary quantity of mucus; and the 
protoplasm within their cells seems to be often killed, 
as may be inferred from the surrounding fluid soon 
becoming pink. It is strange that allied acids act 
very differently : formic acid induces very slight in- 
flection, and is not poisonous; whereas acetic acid of 
the same strength acts most powerfully and is poi- 
sonous. Lactic acid is also poisonous, but causes 
inflection only after a considerable lapse of time. 
Malic acid acts slightly, whereas citric and tartaric 
acids produce no effect. 
