The Chemistry and the Chemical Exploitation of Western 
A r str a li an Plan ts. 
97 
through enzymic reduction, are capable of producing the .same effects. 
Tribuius terrestris L. has been shown in South Africa (81) to contain a 
little nitrite and an appreciable amount of nitrate, and its poisoning symp- 
toms are those of acute asphyxia. The spotted thistle, Silybum Marianum 
(L.) Gaertn., has been known to contain up to 25 per cent, of potassium 
nitrate, calculated on a dry basis, and its toxicity is almost certainly due to 
the reduction of this nitrate to nitrite with the resultant conversion of haemo- 
globin into methaemoglobin. It seems possible that the toxicity of Cynodon 
Dactylon may be due in part to a similar cause, and the possibility may be 
extended to Erythrina cespertilio since some species of this genus are known 
to contain nitrites. 
(d) Photosensitising Plants. 
Photosensitisation of stock does not seem to be of the same importance 
in this State as it does in South Africa or in the Eastern States and New 
Zealand. Steyn and van der Walt (85) have shown that Lantana Camara 
L. is toxic and produces photosei^sitisation, while Louw (86) has isolated 
iantanin from the plant and established it as the photosensitising agent. 
Steyn and van der Walt {Joe. ait.) also record the isolation of a trace of an 
alkaloid from L. erocea Jacq. which produced the characteristic symptoms 
of poisoning by this plant. Quin and Rimington have shown in South Africa 
that the photosensitising action of Medicago denticulata Willd. is due to the 
production of phylloerythrin from chlorophyll in the rumen of the animal 
either by bacterial or protozoan activity. The effect produced by Tribuius 
terrestris is attributed to the same cause and both Medicago minima (L.) 
Grufb. and Clitoris truncatu are similarly suspected. It should be noted, 
however, that the photosensitising action of St. John’s wort, Hypericum 
perforatum L. var. an gusti folium. PC., is due to the presence of a mixture 
of closely related pigments, called hypericin, which in very low concentra- 
tion produces haemolysis on exposure to light of suitable wave length 
(21; 87). Panicum effnsnm R.Br. (21; 60) is also photosensitising, but no 
work appears to have been published on the chemical aspect of this action. 
Trifolium hybridum L. and T. pratense are both recorded by Steyn (60) as 
producing photosensitisation. 
(e) Fish Poisons. 
Fish poisons have been used for centuries by natives in different parts 
of the world and many such materials from Central and South America, 
tropical Africa, India, Malaya, the East Indies and the Pacific Islands have 
been examined systematically by numerous workers to determine their insecti- 
cidal value. Through the influence of the paleotropic flora on Australian 
vegetation, an influence which extended down the eastern portion of Africa, 
it is reasonable to expect that fish poisons similar to those found in Indo- 
Melanesia and East Africa will lie found among our own northern and 
north-western flora. 
No species of the outstanding genera Derris and Loncliocarpus are 
known in this State, but several genera which are known to contain the same 
active principles as Derris do occur in the North-West and Kimberleys. Thus 
some species of Tephrosia have considerable local use as insecticides in 
other parts of the world although they are admittedly not as effective as 
Derris. In Western Australia there are sixteen species of Tephrosia, of 
