270 KUNKEL: FACTORS INFLUENCING TOXICITY OF 
surface of each medium. The cultures were then incubated in a 
room which was kept at a temperature of about 26° C. Observa- 
tions were always made after an incubation period of three days. 
For the purpose of making careful microscopic observations, each 
culture was poured out into a small Petri dish, which could be 
placed on the stage of the microscope. All cultures were first 
observed under a magnification of about two hundred diameters. 
If this observation showed no germination, they were then more 
carefully studied under a magnification of approximately one 
thousand diameters. 
In the tables that follow the plus sign indicates that the spores 
had germinated while the minus sign means that there was no 
germination in the medium in question. The results thus given 
in the tables refer always to the presence or absence of germinated 
spores in the different‘ cultures, after an incubation period of 
three days. The minus sign does not mean that the spores will 
not germinate in the given medium but only that they have not 
germinated after three days. If left in the medium for a longer 
time the spores might germinate. The highest concentration of 4 
salt that will allow germination of the spores within three days 18 
termed the limit concentration for that medium and period of time. 
The toxicity of eleven different chlorides has been tested. 
Chlorides were selected because they have been much studied by 
other investigators and because they are, on the whole, more 
soluble than nitrates, sulphates or other common salts. In 
order to determine the influence of saccharose, glucose, lactose, 
starch and peptone on the toxicity of the several chlorides, I have 
used each of these substances separately in testing the toxicity 
of each inorganic salt. In distilled water and tap water the spores 
of Monilia germinate but produce only a very small amount of 
mycelium. Any of the organic substances used, when added to 
distilled water, greatly increase the growth, and they also tend to 
shorten the time required for germination. Abundant mycelium 
is produced in five per cent. solutions of glucose, saccharose, lac- 
tose, starch or peptone. When chlorides in sufficient concentra- 
tion are added to any of these media the germination of the 
spores is completely inhibited. The approximate value of the 
limit concentration of the different salts in each medium was 
