178
Melanomata in Domesticated Animals
maximum are reported to be fatally toxic in
Oregon and the Alleghany mountains respective-
ly [Lander, 1928]. The leaves contain a tanning
resolvable by acids to yellowish-red rhodoxan-
thine. A reddish colour is obtained by treating
the juice of the leaves with a mineral acid. The
chemical nature of the toxic principle and its
mode of operation are not yet understood.
A cow dead of rhododendron poisoning showed
reddish tint in milk [Eve, 1907].
TREATMENT
Half the ailing animals were given an oleagi-
nous purgative followed by gastric stimulants,
such as nux vomica, gentian and ginger for
three days. The treatment scarcely was neces-
sary, as the untreated animals also recovered
in much the same time, once further ingestion
of the plant was stopped.
DISCUSSION OF RESULTS
As can be seen from the table, after two days'
feeding all the animals evinced a disinclination
for any more of the plant, though given nothing
else to eat. Therefore for five days each animal
was drenched with about 26 lb. of pulverized
leaf and flower suspension in water. No symp-
toms of toxicity were manifested. Since it was
possible that the bulls had developed a tolerance
to this feed and also that there had been a
change in the amount of the toxic principle in
the five days' sample, the sample from the first-
day locality was again utilized. After about
8 lb. of the plant were consumed by the same
bulls in two days, all the symptoms of toxicity
were freshly manifested. Two fresh bulls were
fed over four days about 35 lb. of the second
sample with no untoward symptoms, but, when
the first sample was fed to them as also to the
bulls of the other group, and when only as little
as 6-8 lb. were consumed in two days, all the
symptoms appeared as markedly as before.
Thus we were led to conclude that it was not
a question of tolerance but of the difference in
composition of the two samples that had caused
the failure to produce the symptoms of toxi-
city even when the animals were drenched. It
is well known that climate, soil, season and the
stage of growth affect the toxicity of a plant
[Steyn, 1934]. In this case all things being
almost equal, only the soil condition and the
degree of transmission of toxicity to the progeny
come into prominence, for the two localities were
fairly distant. This finding seems to be in
agreement with that of Steyn [1932] and
Couch [1932].
SUMMARY AND CONCLUSIONS
Two samples of rhododendron arboreum from
two different localities were used in feeding ex-
periments on bulls, sheep and goats. Of these
one sample was definitely toxic and the other
was not. Soil condition is incriminated in the
loss of toxicity of the second sample. The plant
is not lethally toxic.
REFERENCES
Couch. J. F., (1932). U. S. Dept. Agric., Leaflet, 88.
Eve, H. B. (1907). Vet. Rec., 630.
Kirtikar, K. R., and Basu. B. D. (1933), Indian Med.
Plants. 2nd Edn. Lalit Mohan Basu. Allahabad
Lander, D. G. (1928). Vety. Toxicology. 2nd Edn.,
Bailliere Tindall & Cox., London.
Steyn, D. G. (1932). 18th Rep. Dir. Vet. Ser. Anim.
Industr. Union of S. Africa. 899.
—(1934).
Toxicology of Plants in South
Africa. Central New Agency, S. Africa.
MELANOMATA IN DOMESTICATED ANIMALS*
By M. Y. MANGRULKAR, M.Sc., M.R.C.V.S., D.T.V.M. (Edin.),
Imperial Veterinary Research Institute, Mukteswar
(Received for publication on 11 May 1942)
(With Plates XIV and XV)
THE subject of melanomata has always been
a vexed problem for the oncologist, the phy-
siologist and the embryologist alike. Although a
good deal of work has been done on the histogene-
sis of the specific tumour cell, the melanoblast
and on the origin of the tumour itself, it has, if
anything helped to make the position more be-
wildering than before by introducing into the
field several points on which considerable
difference of opinion exists. Indeed, apart from
those who believe in the existence of a specific
neoplastic cell, there are those who claim that
there is no such thing as a melanoblast, and that
melanotic neoplasms are products of structural
and functional changes in the ordinary cells of
*Paper presented before the Veterinary Section of the
25th Session of the Indian Science Congress, in January
1938, at Calcutta.