98 
E. M. Watson. 
which two, T. purpurea Pers. and T. rosea F. Muell. ex Benth., are known 
to be poisonous. These two species at least should be investigated for their 
insecticidal value. In the same category is the genus Barringtonia and 
possibly the genus Terminalia. 
The bark of Careya australis F. Muell. is used as a tish poison in Queens- 
land and Northern Australia and material from Arnhem Land has been 
examined (88) for insecticidal properties but found to be without toxic effects 
on Aphis nunicis. The bark of Acacia salicina is recorded by Hurst (21) as 
being used as a fish poison. 
(f) Miscellaneous Poisons. 
Abrus precat or ius L. contains two toxic proteins, a paraglobulin and a 
phytalbumose, the mixture being known as abrin. Abrin is not necessarily 
poisonous when taken orally but it is highly toxic when injected. It has 
been used therapeutically in treatment of opacity of the cornea and granu- 
lation of the eyelids, but the inflammation it produces is dangerous and some- 
times difficult to control. The introduced Cucumis myriocarpus Naud. has 
frequently been reported toxic to stock and human beings. Finnemore has 
shown the ab-enee of prussic acid and South African workers have separated 
several toxic materials from the fruit. Quin isolated in 1928 a non-alkaloidal, 
non-glycosidal substance which was highly toxic to animals, whether given 
orally or by injeclion. In 1933 Rimington separated the amorphous very 
toxic substance eueumin from this and other species of Cucumis. Subse- 
quently Rimington and Steyn (89) isolated the apparently pure compound 
C., s H,.,O s and showed that it was probably a dilactone. Pteridium aquilinum 
(L.) Kuhn., the bracken, which is toxic to cattle and horses, is stated by 
Steyn (60) to contain pteritannie acid (identical with fllicic acid from 
Dryopter'.s Fi'ix-mas) as its main active principle. 
Leonotus leonurus R. Br., which is smoked by natives in South Africa 
like Indian hemp and which produces a similar stupefying effect, is recorded 
by Watt and Breyer-Brandwijk (32) as containing a dark green resin 
which is probably responsible for the narcotic action. The same authors 
;il so refer to the separation of two phenolic substances from the reddish 
leaf oil. The prolonged blood-clotting time associated with the eating of 
Melilotus alba Desr. and probably M. indica All., is discussed by Hurst (21). 
The presence of coumarin has been shown to have a bearing on the ability 
of the clover to become toxic and a specific substance has been isolated 
from spoiled clover which inhibits blood-clotting. 
Oxalic acid and oxalates are widely distributed in the plant kingdom, 
often in sufficient quantity to cause stock poisoning. Many species of Bumex 
and Ox alis, for example, contain enough to produce poisoning if eaten to 
excess and Salsola Kali is known to contain a considerable amount of the 
acid. 
There are many plants which have been proved toxic but no information 
is available concerning their active principles. In some cases, a knowledge 
of the poisonous constituents of other species belonging to the same or to 
related genera may be of value as a guide, but in others there is little evi- 
dence to suggest possible lines of attack. Amongst the more important of 
these plants are Anagallis femina Mill., Bryonopsis laciniosa , Cryptandra 
leucophractu Schlecht., Didiscus glaucif alius F. Muell. (which contains 
