384 Tloyal Society : — 



«- + c'-> 36% and the memoir contains a figure showing the form of 



the surface for the case in question. The equation of the surface is 



obtained by the elimination of X, Y, Z between the above-mentioned 



X' Y" Z" 

 equations and the equation —;--)- — ^ — = 1, as aheady remarked. 



This is reduced to the determination of the discriminant of a quartic 

 function, and the equation of the surface is thus obtained under 

 the form P— 27J'-=0, where I and J are given functions of the co- 

 ordinates. 



"Some llemarks on the Physiological Action of the Tanc/hinia 

 venenifera.'" By Professors A. Kblliker of Wiirzburg, and E. Peli- 

 kan of St. Petersburgh. 



The famous poison-tree of Madagascar was described for the first 

 time by Aubert du Petit Thouars in his ' Genera Madagascarensia,' 

 under the name of Tanghinia venenifera. At a later period, Sir W. 

 Hooker published a good description, with a figure of this tree, named 

 by him Cerbera Tanghin (see Botanical Magazine, pi. 2968) ; so that 

 nothing is wanted with regard to the botanical knowledge of this 

 plant. On the other hand, the physiological effects of its poisonous 

 parts have not been hitherto investigated. All we know is, that the 

 fruit of the Tanghinia is a strong poison, and is used in Madagascar 

 as an ordeal poison in the most strange and revolting way. The 

 only experiment on animals made by Ollivier, showed that 1 2 grains 

 kill a dog in some hours ; but this experiment gave no further in- 

 sight into the real action of the Tanghinia. We hope, therefore, that 

 the Royal Society will take some interest in the experiments which 

 we undertook with this poison, of which the following is a short 

 abstract. 



The poison used by us was the alcoholic extract of the leaves and 

 small stems of the Tanghinia, prepared from dried specimens, which 

 Prof. Pelikan had received from Count Seyderitz of Mecklenburg. 

 About one centigram of this extract was sufficient to show the full 

 effect of the poison on frogs, when introduced into a wound of the 

 back. It acted also when given by the mouth, but in this case a 

 somewhat larger dose was required to procjuce a full effect. 



The observed symptoms were the following : — 



1 . First of all, viz. in about 5 to 1 .') minutes, the heart was affected 

 and stopped in its action, in such a way that the ventricle became 

 contracted and very small, whilst the auricles remained dilated, but 

 were also paralysed. 



2. The vohnitary and rejlex movements were at first not at all 

 affected ; but some time — from half an hour to one hour — after the 

 paralysis of the heart, they became weaker and weaker, and gradually 

 ceased totally without any sign of spasms or tetanus . 



3. In the third place, the Tanghinia has a great influence upon the 

 voluntary muscles, which become paralysed. This action begins very 

 soon, and we have been able to show, with the aid of the myogru' 

 jphion of Volkman, that as soon as the heart is paralysed, the muscles 

 also begin to lose their force. Nevertheless, the total paralysis of 



