SYPHILIS 249 



the microbes. If the phagocytes are resistant they are able to 

 produce enzymes which attenuate the toxins, thus providing 

 antitoxins, and recovery follows. If their resisting power is low, 

 they are paralysed or killed, enzymes are not produced, a scale of 

 attenuated toxins is not provided, and the individual does not 

 react, but perishes. The tobacco smoker does not acquire increased 

 resisting power against any other toxin, for example, he is not 

 rendered more resistant to opium. Similarly, since the toxins of 

 every disease differ from those of every other, immunity (i.e. 

 labituation) acquired against any one disease confers no increase 

 of resisting power against any other. 



416. Syphilis, which has been curiously neglected by students 

 of acquired immunity but which is often quoted by medical 

 supporters of the Lamarckian doctrine, affords very instructive and 

 llustrative data. The disease is caused by a microbe, the spirochete 

 pallidum. It has been said that offspring may be infected by 

 either parent, but certainly infection is much more common through 

 the mother. If it be true that healthy mothers sometimes bear 

 infected children, then, in such cases, the microbes must have been 

 travelling with the fertilizing spermatozoon, or in some other way 

 which I cannot imagine have entered the ovum without invading 

 the maternal tissues. The microbe of Texas fever, a disease of 

 cattle, is . known to travel with the germ-cells of the tick with 

 which the cattle are infested. The child in utero, is, rightly 

 speaking, merely a parasite on the mother. It adheres to her 

 by the placenta, through which it receives nutriment, and in which 

 the thin-walled maternal and fcetal vessels lie in close contact so 

 that fluids with dissolved solids and gases pass from one to the 

 other, whereas solids such as blood corpuscles and microbes do not. 

 In some diseases of which syphilis affords by far the greater 

 number of examples, injury to the placental vessels may occur and 

 result in the passage of solids, for example microbes. Apparently 

 the toxins of syphilis are but slowly elaborated and are not very 

 virulent. Consequently the disease is of gradual development and 

 of long duration. It would appear that the microbes, while they 

 are yet few in number, are at first confined to the place of entry, 

 where they are protected by their concentrated toxins. Later 

 when they have multiplied and the resistance of the phagocytes 

 has been, for the time, overcome by the increased abundance of 

 toxins, they spread over the whole system. The mother, then, 

 gradually acquires immunity. Her phagocytes become tolerant 

 of the toxins and produce enzymes which attenuate them. A 



