ESSAYS ON BACTERIOLOGY. 29 



and inoculations are made in order that if the bacteria 

 should escape ocular detection they may still be 

 found. On the strength of these researches some 

 have claimed to prove the passage of the germs to the 

 fetus, while some, conducting their studies with every 

 precaution, have reached only negative results, and 

 have believed that the apparent exceptions in the 

 hands of others were due to contamination. A report 

 made to the Paris Academy about a year ago was en- 

 tirely negative, and this has been the rule. The well- 

 known case of Johne, who proved fetal tuberculosis 

 in a calf, stands alone unquestioned. 



The end has not yet been reached. There are still 

 claims and counter-claims, strong beliefs and influen- 

 tial skepticism. Certainly some of the infectious dis- 

 eases seem to be transmitted by heredity, or at least to 

 be congenital. As regards tuberculosis, there has 

 been an unmistakable growth of the opinion that the 

 disease is to be looked upon as an infection, not an in- 

 heritance; that the ideas of its heredity have been 

 much exaggerated; that it is comparatively rarely 

 transmitted to the fetus — ^perhaps never. How much 

 of the hopes of preventive medicine depend upon the 

 truth of these opinions is at once apparent. Whether 

 we shall fail to reach positive knowledge, and, opinion 

 wavering, the pendulum shall swing again toward its 

 former position, remains to be seen. In the mean- 

 time let us get a clear view of the facts already estab- 

 lished, give due credit and appreciation to the sincere 

 and earnest efforts for the solution of the great ques- 



