ON THE ORIGIN OP LIFE. 



221 



upon more and more as machines, carefully built up, and 

 delicately adjusted, capable when supplied with proper 

 material of doing such and such work, and of turning out so 

 much finished product, much of it useful, but much of it not 

 only of the nature of waste, but in part actually deleterious. 

 Following the lead of the physiologist, it was insisted that 

 each organism had its exact structure and function defined and 

 regulated to one pattern, and that, although in accordance 

 with the doctrine of evolution slight variations may take place 

 in the individual which may become more accentuated in its 

 progeny, such variations, to become marked and permanent, 

 must be present through a long succession of generations. 

 When we come to consider certain of the changes produced 

 during the course of disease, however, something far more 

 striking and apparently infinitely more important, from our 

 point of view, emerges. The animal body, endowed with life, 

 may, under the influence of certain substances often classified 

 as proteids or albuminoids, and especially those of a poisonous 

 nature, become greatly modified in respect to its reactions to 

 these substances. 



Everyone has heard of antitoxins, but how many of us realize 

 that in their production in the animal body we have probably 

 one of the strongest of our proofs of the existence of some- 

 thing more than any mere chemical or chemico-physical process, 

 especially since Ehrlich and Weigert were able to demonstrate 

 that these antitoxins are the result of some specific reaction 

 between proteid toxins and the tissues of the body ? Let us 

 take a definite example. If a horse which is extremely 

 sensitive to the poisonous effects of the diphtheria toxin, a 

 poison proved by Sidney Martin and others to be of a proteid 

 or albuminoid nature, be treated with very minute, but 

 gradually increasing doses of this toxin, its tissues may become 

 so modified that, although at first they would have been unable 

 to withstand the action of some arbitrary quantity determined 

 by experiment and called the " Minimal Lethal Dose," coming 

 out, say, at fifteen drops, they will, after carefully graduated 

 injection with this same toxin, withstand the action of 15,000 

 drops of it. The blood of an animal so treated is found to 

 contain a substance which, even when mixed with the toxin in 

 a test tube, neutralises the activity of the toxin and renders it 

 harmless; and the same thing occurs when the blood is injected 

 into a patient suffering from diphtheria. We thus see that the 

 toxin injected into the horse has caused some reaction in the 

 tissues of that animal, as a result of which they give off a 



