242 ACQUIRED IMMUNITY 



does not necessarily retain its power of tolerating large doses of 

 toxin when these are injected. 



405. (o) Syphilis is a disease of such long duration that it may 

 cover several pregnancies in a woman. As a rule, the infants that 

 are born during her illness suffer less and less as the disease pro- 

 gresses. Thus, speaking generally, if she have rapidly recurring 

 pregnancies, at first she miscarries early in the pregnancy, then a 

 dead but fully developed child is born, then a child which appears 

 healthy, but soon wastes and dies, then one who survives but ex- 

 hibits signs of disease, and lastly one which shows no signs of it. 

 Even if both parents be diseased the successive children tend to suffer 

 less and less. If a diseased woman bears children to successive men, 

 then, whether the male parents be diseased or not, her successive 

 children tend to suffer less and less as time goes on till they do not 

 suffer at all. But, if a diseased man has infected children by a suc- 

 cession of women who were not previously diseased, the last child 

 tends to suffer as severely as the first. Evidently, then, while a woman 

 may mitigate the disease for her offspring, a man cannot. Though 

 a woman suffering from the disease tends to confer immunity on 

 her surviving children, yet a woman recovered from it confers none 

 on children that are not infected at least, judging from the 

 analogy of other diseases, so we must suppose, for a mother who 

 has suffered from and acquired immunity against measles, scarla- 

 tina, smallpox, or any other malady, confers no immunity on her 

 offspring. A woman who has recovered from syphilis has never 

 been known to bear a diseased child to an infected father. But a 

 woman who has not, and never has had the disease, may bear an 

 infected child to such a mate. The bearing of the infected child 

 confers immunity on her, for she never contracts syphilis when 

 suckling it, though healthy wet nurses may. A diseased woman 

 may bear a healthy child which, presumably, is immune, since it 

 does not acquire the disease when suckled by her. The proof that 

 it is not infected is afforded by the fact that it does not convey the 

 disease to a healthy wet nurse. 



406. (/) Snake poison (a toxin) may be swallowed in doses a 

 thousand times larger than would suffice to cause death if injected 

 under the skin. Immunity instead of death results. The Bushmen 

 of South Africa are declared on good authority to seek and obtain 

 safety from snake-bite by swallowing poison glands. Snake venom 

 artificially attenuated is now successfully used as an antitoxin for 

 the cure of snake poisoning, (q) Nicotine, opium, strychnine, and 

 other vegetable poisons, many of which are used as medicines, are, 



