274 KUNKEL: FACTORS INFLUENCING TOXICITY OF 
Calcium is one of the most important plant nutrients. It also 
has great value for counteracting the toxicity of other salts. The 
above table shows how its toxicity varies in the different media. 
Its poisonous action in starch is the same as in saccharose and 
only slightly less than in peptone. It is most toxic in lactose and 
least toxic in glucose. The average limit concentration is .44 
molar. 
TABLE V 
THE TOXICITY OF BARIUM CHLORIDE IN SACCHAROSE, GLUCOSE, LACTOSE, STARCH, 
AND PEPTONE MEDIA 
Saccharose 5% Glucose 5% | Lactose 5% Starch 5% Peptone 5% 
GM. | Growth! 6 x6 conc, | O¥"™ | G.at, Cone, | OME) c.at, Cone. | fame) GM. | Gren 
BaCl, 3 Days BaCl, 3 Days BaCl, 3 Days. BaCl, |3 Days | BaCl, |3 Days 
ey “50 - 55 ss 80 a hy 
Sh ae es 50 ~ .70 45 
te A Seine +30 _ 4S aot 66 = ue ‘a 
pst ae pans tr -40 _ 150 rae Pe 
go | = .10 + 35 4 .40 ii 30 SS 
25 + .09 - .30 + 30 wa gee ce 
st = .08 + +25 =“ .20 ao .20 a 
15 ee 07 + .20 4. IO cs 5 a 
pg oat is - =s + .09 oA ea 
.08 + O05 + -I0 + .08 | os 05 aa 
Table V gives the toxic values of barium chloride. Although 
barium is much like calcium chemically it is not a plant nutrient. 
Barium is on the whole much more toxic than calcium. It is less 
toxic in lactose media than in glucose. In this respect it is quite 
different from calcium chloride which is more than five times as 
toxic in lactose as in glucose. The average limit concentration is 
.26 molar. The toxicity of barium chloride is influenced less by 
the different media than that of any of the other chlorides which 
have been used. In saccharose, glucose, starch and peptone it 
is more toxic than calcium chloride. In lactose media, however, 
calcium chloride is more than three times as toxic as barium 
chloride. It is worth noting that the toxicity of the five chlorides 
as shown by the above tables is, on the average, as great in peptone 
as in the other media. Their toxicity is least in glucose and 
greatest in lactose. They are more toxic in peptone than in 
saccharose or glucose, although peptone is a much more favorable 
medium for the growth of the fungus. This shows that in some 
