A number of other substances are sometimes credited with being racial poisons.
The poison of _Spirochæte pallida_, the microörganism which causes syphilis, has been widely credited with a directly noxious effect on the germ-plasm, and the statement has been made that this effect can be transmitted for several generations. On the other hand, healthy children are reported as being born to cured syphilitics. Further evidence is needed, taking care to eliminate cases of infection from the parents. If the alleged deterioration really occurs, it will still remain to be determined if the effect is permanent or an induction, that is, a change in the germ-cells which does not permanently alter the nature of the inherited traits, and which would disappear in a few generations under favorable conditions.
The case against lead is similar. Sir Thomas Oliver, in his _Diseases of Occupation_, sums up the evidence as follows:
"Rennert has attempted to express in statistical terms the varying degrees of gravity in the prognosis of cases in which at the moment of conception both parents are the subjects of lead poisoning, also when one alone is affected. The malign influence of lead is reflected upon the fetus and upon the continuation of the pregnancy 94 times out of 100 when both parents have been working in lead, 92 times when the mother alone is affected, and 63 times when it is the father alone who has worked in lead. Taking seven healthy women who were married to lead workers, and in whom there was a total of 32 pregnancies, Lewin (Berlin) tells us that the results were as follows: 11 miscarriages, one stillbirth, 8 children died within the first year after their birth, four in the second year, five in the third year and one subsequent to this, leaving only two children out of 32 pregnancies as likely to live to manhood. In cases where women have had a series of miscarriages so long as their husbands worked in lead, a change of industrial occupation on the part of the husband restores to the wives normal child-bearing powers." The data of Constantin Paul, published as long ago as 1860, indicated that lead exercised an injurious effect through the male as well as the female parent. This sort of evidence is certainly weak, in that it fails to take into account the possible effects of environment; and one would do well to keep an open mind on the subject. In a recent series of careful experiments at the University of Wisconsin, Leon J. Cole has treated male rabbits with lead. He reports: "The 'leaded' males have produced as many or more offspring than normal fathers, but their young have averaged smaller in size and are of lowered vitality, so that larger numbers of them die off at an early age than is the case with those from untreated fathers."