VEGETABLE AND ANIMAL POISONS 169 



going on in the animal's body. Again, too much importance 

 must not be attached to loss of toxicity by toxins at relatively 

 low temperatures. This is not true of all toxins, and further- 

 more many proteids show a tendency to change at such 

 temperatures ; for instance, if egg albumin be kept long 

 enough at 55 C. nearly the whole of it will be coagulated. 

 We must therefore maintain an open mind on this subject. 



Similar Vegetable and Animal Poisons. Within recent years it has 

 been found that the bacterial poisons belong to a group of toxic bodies 

 all presenting very similar properties, other members of which occur 

 widely in the vegetable and animal kingdoms. Among plants the best- 

 known examples are the ricin and abrin poisons obtained by making 

 watery emulsions of the seeds of the Ricinus communis and the Abrus 

 precatorius (jequirity) respectively. From the Robinia pseudacacia 

 another poison robin belonging to the same group is obtained. The 

 chemical reactions of ricin and abrin correspond to those of the bacterial 

 toxins. They are soluble in water, they are precipitable by alcohol, but 

 being less easily dialysable than the albumoses they have been called 

 toxalbumins. Their toxicity is seriously impaired by boiling, and they 

 also gradually become less toxic on being kept. Both are among the 

 most active poisons known ricin being the more powerful. When they 

 are injected subcutaneously a period of twenty-four hours usually elapses 

 whatever be the dose before symptoms set in. Both tend to produce 

 great inflammation at the seat of inoculation, which in the case of ricin 

 may end in an acute necrosis ; in fatal cases hsemorrhagic enteritis and 

 nephritis may be found. Both act as irritants to mucous membranes, 

 abrin especially being capable of setting up most acute conjunctivitis. 



It is also certain that the poisons of scorpions and of poisonous snakes 

 belong to the same group. The poisons derived from the latter are 

 usually called venins, and a very representative group of such venins 

 derived from different species has been studied. To speak generally 

 there is derivable from the natural secretions of the poison glands a 

 series of venins which have all the reactions of the bodies previously 

 considered. Like ricin and abrin, they are not so easily dialysable as 

 bacterial toxins, and therefore have also been classed as toxalbumins. 

 Their properties are also similar ; many of them are destroyed by heat, 

 but the degree necessary here also varies much, and some will stand 

 boiling. There is also evidence that in a crude venin there may be several 

 poisons differently sensitive to heat. All the venins are very powerful 

 poisons, but here there is practically no period of incubation the effects 

 are almost immediate. An outstanding feature of the venins is the 

 complexity of the crude poison secreted by any particular species of 

 snake. C. J. Martin in summing up the results of many observers has 

 pointed out that different venoms have been found to contain one or 

 more of the following poisons : a neurotoxin acting on the respiratory 

 centre, a neurotoxiu acting on the nerve-endings in muscle, a toxin 

 causing haemolysis, toxins acting on other cells, e.g. the endothelium of 

 blood-vessels (this from its effects has been named hsemorrhagin), 

 leucocytes, nerve-cells, a toxin causing thrombosis, a toxin having an 

 opposite effect and preventing coagulation, a toxin neutralising the 

 bactericidal qualities of the body fluids and thus favouring putrefaction, 

 a toxin causing agglutination of the red blood corpuscles, a proteolytic 



