74 Infection 



liberated into the body juices so as to be conveyed by the 

 circulatory system to all parts of the body. Those cells 

 most susceptible to its action are then first or most pro- 

 foundly impressed by it, and definite responses brought 

 about. Thus, the soluble toxin of tetanus causes no visible 

 reaction in the cells with which it first comes into contact 

 at the seat of primary infection, because these cells are 

 either less susceptible to its influence, or are less well able 

 to show its effects, than the cells of the nervous system to 

 which it is secondarily carried by the blood. 



SPECIFIC AFFINITY OF THE CELLS FOR THE TOXINS. 



The cells of the connective tissue in which the tetanus 

 bacillus is living show little reaction, but the motor cells of 

 the central nervous system, having a greater affinity for it, 

 are profoundly impressed, so that convulsions of the con- 

 trolled muscular system are brought about. This special 

 excitation of the nerve cells is specific because no other 

 bacterio-toxin is known to produce it and it is attributed 

 to special selective affinities of the nerve cells for the poison. 

 This affinity has its analogue among the poisons of higher 

 plants, thus, strychnin has a similar selective affinity and is 

 also said to be specific in action upon the motor cells. 



The venoms of various serpents, especially the cobra, also 

 have specific reactions, the cells of the respiratory centers 

 seeming to be most profoundly affected by them. 



The diphtheria bacillus, when observed in ordinary throat 

 infections, is seen to produce a pseudomembranous angina 

 which results in part from an irritative local action of the 

 organism, which it shares in common with many others, 

 and in part from some coagulating product which jt shares 

 in common with a few pneumococcus, streptocococus, etc. 

 Neither of these reactions is specific, but subsequent to these 

 early manifestations comes depressant action on the nervous 

 cells with palsy, peculiar to the products of the diphtheria 

 bacillus, and therefore specific. 



It is upon the peculiar, specific reactions of the bacterio- 

 toxins and the peculiar susceptibility of certain cells to this 

 action that the production of distinct clinical manifestations 

 depends. 



