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 tlois 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, SpirochcEta 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, a 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. 



