Oct. 16, i 9 x6 Effects of Nicotine as an Insecticide 119 
also be made between the fish eggs used by Loeb and the fat cells and 
cenocytes employed by the present writer. All these facts seem to indi¬ 
cate that either lack of oxygen or the presence of nicotine around the cells 
kills physically rather than chemically. The following paragraphs will 
considerably strengthen this statement. 
It is well known that different fluids have different osmotic pressures, * 
and this is also true for the blood of different animals. In order that 
tissues removed from various animals might be kept alive for some time, 
Lewis (15) has shown that they must be placed in fluids having different 
osmotic pressures. Endeavoring to make a fluid having an osmotic 
pressure equal to that of the blood in a grasshopper, Lewis used sea 
water, distilled water, grasshopper bouillon, sodium bicarbonate, and 
dextrose. The effect of osmotic pressure on cells is best illustrated by 
using red corpuscles. According to Cushny (6, p. 304-314), water 
passes into these cells readily and when placed into distilled water they 
swell up and burst, but when placed into an aqueous solution of sodium 
chlorid having an osmotic pressure greater than that of their contents, 
they shrink because the contained salts are unable to retain water 
against a higher concentration outside. A change brought about in 
the osmotic pressure of the blood might be a probable explanation of 
the death of the honeybees recently fed various salts by the present 
writer (18). 
There are several theories regarding the manner in which drugs and 
powerful poisons affect the cells. Cushny has briefly summarized 
them about as follows: (1) Some drugs enter into definite chemical com¬ 
binations with the constituent protoplasm; (2) some drugs act on the 
cells by changing the relation of the cell constituents in which they 
are dissolved; (3) some drugs alter the surface tension of the cells in 
relation to the surrounding fluids; (4) a few powerful drugs may act by 
altering the surfaces of the cells without penetrating into the interior; 
(5) many drugs may change the intracellular membranes; and (6) other 
drugs may reduce the permeability of the cellular membranes by altering 
their electric charges. Cushny says (6): 
From the present confusion the only legitimate conclusion seems to be that the 
activity of drugs depends on a large variety of factors and that pharmacological action 
can not be brought under any one law, either chemical or physical. 
Shafer (21) has added another view which should be classified with 
the chemical ones, for it deals with the enzym-like cell constituents 
which accomplish oxidation. He thinks that contact insecticides, 
nicotine included, deleteriously affect the activities of the reductases, 
catalases, and oxidases in an unequal degree, thereby disturbing the 
natural or normal balance of the activities of these enzym-like factors. 
