686 MICROBIOLOGY OF DISEASES OF MAN AND DOMESTIC ANIMALS 



not inheritance. If the microorganisms were present they would be 

 immediately incorporated within the new developing embryo. If the 

 microorganism ever did find its way into the human or mammalian 

 germ cells it would be a mechanical impossibility for the cells of the 

 embryo to divide and multiply in proper manner. Such pathogens 

 would rapidly destroy the developing cells in the embryo. It is true 

 that the offspring of certain individuals are born diseased. For ex- 

 ample, children are not infrequently born with syphilis and tuberculosis. 

 At first thought it might seem that this is inheritance but on careful 

 analysis it will be found that the mother is either syphilitic or tubercu- 

 lous. Furthermore, the focus of the infection is most frequently in the 

 uterus and the microorganisms are transferred to the unborn offspring 

 by means of the fetal circulation. This condition is what is known as 

 antenatal acquirement; it is not heredity. It is absolutely impossible for 

 the male to communicate any disease to the offspring unless the female 

 is first infected. Colle years ago formulated a law which bears his name 

 in which he stated that a father could communicate syphilis to his child 

 without the mother being infected. This law has been disproved since 

 the introduction of the new serum tests for syphilis and it can be posi- 

 tively demonstrated in all such cases that the mother is infected. Ante- 

 or prenatal acquirement may then be recognized. What can be said 

 in regard to the predisposition to a definite infectious disease? There 

 is a question as to whether true predisposition does exist. Many 

 cases are on record to show that disease seems to run in families and in 

 localities. For example, tuberculosis and cancer are frequently said 

 to be subject to inheritance or to predisposition in certain cases. It 

 can be easily seen that if one parent is diseased the germ cell of the 

 parent will be less healthy and when combined with a normal healthy 

 germ cell of the other parent will not give rise to as healthy an individual 

 as when both cells are from healthy individuals. Again, the result when 

 the germ cells of both parents are unhealthy, due to the parents being 

 unhealthy, is evident. Predisposition seems to resolve itself into the 

 inheritance of a weakened constitution, a constitution which will not 

 withstand the ordinary infections easily. It seems not to be a predis- 

 position to any particular disease but a predisposition to all diseases, 

 infectious and metabolic. Diseases such as tuberculosis are so 

 prevalent that it is very possible that infection may take place and it be 

 interpreted as inherited because the parent died of the same cause. 



