ALCOHOL, DISEASE, AND HEREDITARY DEFECTS 293 
It is important to carry experiments through several generations 
and to experiment with a large number of substances and upon a 
variety of forms of life. If we knew the conditions under which 
new variations arise in plants and animals the information 
would not only be of great importance in relation to problems of 
heredity and evolution, in general, but it would be of especial 
value to the student of the trend of our own racial development. 
The evidence that the toxins of disease may unfavorably 
affect the inheritance of human beings is at present very inade- 
quate. In the light of such facts as have just been discussed such 
an influence would seem probable a priori. The disease whose 
hereditary effects are the most obvious is syphilis, which may be 
transmitted from parent to offspring through one or two genera- 
tions and possibly more. It is not necessary to describe the disas- 
trous consequences to offspring resulting from this terrible 
malady. It is only too well known as a very potent cause of abor- 
tions, stillbirths, early deaths, and much misery to those to whom 
it does not mercifully prove fatal. The transmitted effects of 
parental syphilis, however, are mainly due to the infection of the 
offspring by the organism, Spirocheta pallida, which is now 
demonstrated to be the cause of this disease. Whether syphilis 
produces a true blastophthoric effect is a matter very difficult to 
ascertain, because such an influence would be so closely associated 
with the direct results of the disease itself. There is no evidence 
at present available which would warrant us in regarding syphilis 
as the cause of defective inheritance in the proper significance of 
this term. 
The same conclusion may be drawn for tuberculosis, malaria 
and other diseases which are often rather loosely spoken of as 
“racial poisons.” It may be more or less probable, @ priori, 
that they may permanently impair human germ plasm and give 
rise to strains with a degenerate inheritance, but our knowledge 
on this important problem is still too meager to justify positive 
statements. 
