ABSTRACTS 407
symptoms have been experimentally induced in animals such as rats, guinea-pigs and
sheep under laboratory conditions by feeding them with varying doses of fluorine. Affect-
ed animals recovered on changing the feed and thus stopping the fluorine intake.
Some of the physiological reactions of a continued sublethal dosage of fluorine are
reduced appetite, less utilization of food, loss of weight, reduced rate of growth, un¬
thriftiness, diarrhoea, diuresis, anaemia, photophobia, transitory glucosuria, anorexia,
etc. Histological symptoms characteristic of osteomalacia, hypoplasia of the enamel
and dentine and degenerative changes in the kidney, liver, suprarenals, heart, muscle
and nervous system also occur.
Chemically the bones and teeth are the most affected. The concentration of
fluorine in normal bone ash is 0.01-0.15 per cent. In cases of fluorine intoxication,
with no obvious symptoms, it is 10 to 15 times as much and in clinical cases, 15 to 30
times as much and in exceptional cases about 70 times more than in normal bones, the
bone ash containing about 2 per cent fluorine and the teeth about 1 per cent. Highest
concentrations up to 2.7 per cent are found in exostoses, the epiphysis, the cancellous
bones and the compact shaft containing lesser quantities in descending order.
Normal tissues of hens and cows contain 0.5 to 1.0 mg. fluorine per 100 gm. dry
matter. Due to the ingestion an increase of 2 to 5 times has been noticed, while in one
case a cow's thyroid had as much as 160 mg. fluorine per 100 gm. Under similar con-
ditions of ingestion, the blood of cows shows an increase from 0.2 to 0.6 mg. per 100 c.c.
and that of hens from 0.0 to 0.15 mg. In the egg an increase from 0.05 to 0.2 mg. per
100 gm. has been obtained, most of it being in the lipoid fraction of the yolk. Regarding
milk, opinion is divided. Studies have also been made upon the effect of fluorosis on
coagulation time of blood, the phosphatase content of kidney and plasma, the serum,
calcium and phosphorus, the retention of calcium and phosphorus and the vitamin C
content of various organs.
The minimum quantities of fluorine that induce the syndrome of chronic fluorosis
are 70 mg. per day per kg. body-weight for the hen, 10 mg. for the pig, 3 mg. for the
cow and 3 mg. for the sheep. Dental changes are effected in rats with 1 mg. per day while
20 mg. were required for chronic symptoms to develop.
Sodium fluoride and sodium fluosilicate are the most toxic, rock phosphate and
phosphatic limestone slightly less toxic and cryolite and calcium fluoride are the least
toxic.
Toxicity decreases with age. It increases when ingested in solution, 20 mg. as
solid and 0.5 mg. in solution being equal in effect. It is decreased by a simultaneous
calcium phosphate, aluminium chloride or green grass supplement. It increases with
an imbalanced food intake or undernourishment. Ingestion of desiccated thyroid in-
creases the toxicity. Intermittent intake lessens toxicity.
The author concludes by suggesting that care should be exercised in selecting the
phosphate supplement for stock. Calcination by steam, if economical, would solve
the problem better by reducing the fluorine content. Dairy cows fed at 2 mg. fluorine per
kg. body-weight per day for 6 years showed no deleterious effects. Careful disposal
of the emanations from chemical factories would avoid the contamination of the atmos-
phere, vegetation and water supply of the localities. The disease does not occur in
localities where the soil contains less than 20 mg. fluorine per 100 gm. [P. A. S.]
Effect of temperature on size of eggs from pullets in different latitudes.
D. C. WARREN (1939). J. Agric. Res. 59, 441-452.
I N order to secure data for the construction of annual egg size curves for birds main-
tained under various environmental conditions, records were obtained from scienti-
fic workers in different parts of the United States of America, the Philippine Islands,
Canada and Scotland. In all instances the records were selected from pullets which
laid consistently throughout the year. Freak specimens such as double-yolked or yolk¬
less eggs were not included in the calculations. In each instance the egg weights were
plotted against the maximum day temperature. A comparison of the various groups
of annual egg size showed clearly that the temperature was a very important factor
in determining the type of figure obtained. In most instances the egg size increased
fairly rapidly during the first few months but at one station near the Equator where