196 THE TOXINS PRODUCED BY BACTERIA 



bouillon culture, further chemical substances are formed in the 

 body before the actual toxic effect is produced. Too much 

 reliance must not be placed on such an argument, for in the 

 case of tetanus, at least, the delay may be explained by the fact 

 that the poison apparently has to travel up the nerve trunks 

 before the real poisonous action is developed. Further, with 

 some poisons presently to be mentioned which are closely allied 

 to the bacterial toxins, an ' incubation period may not exist. 

 It would not be prudent to dogmatise as to whether the toxins 

 do or do not belong to such an ill-defined group of substances 

 as the ferments. It may be pointed out, however, that the 

 essential concept of a ferment is that of a body which can 

 originate change without itself being changed, and no evidence 

 has been adduced that toxins fulfil this condition. Another 

 property of ferments is that so long as the products of fermenta- 

 tion are removed, the action of a given amount of ferment is 

 indefinite. Again, in the case of toxins no evidence of such an 

 occurrence has been found. A certain amount of a toxin is 

 always associated with a given amount of disease effect, though 

 a process of elimination of waste products must be all the time 

 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. It has been found that 

 the bacterial poisons belong to a group of toxic bodies all present- 

 ing 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 JRobinia 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. 



