PRACTICAL RESULTS OF BACTERIOLOGY. 749 



In 401 cases of children under the age of two years, in which the 

 serum treatment was used on the first and second day, the mor- 

 tality rate was 11*8, in contrast with 39*7 where under similar 

 conditions it was not used. Of 2,556 children between two and 

 ten years of age, the death-rate was 4 per cent after antitoxin 

 treatment, instead of 15*2 per cent in the other group. 



Prof. Welch very truly and forcibly remarks : " The discovery 

 of the healing serum is entirely the result of laboratory work. 

 It is an outcome of the studies of immunity. In no sense was the 

 discovery an accidental one. Every step leading to it can be 

 traced, and every step was taken with a definite purpose and to 

 solve a definite problem." 



The importance of prompt treatment in this very fatal malady 

 is shown by the following figures which we take from Prof. 

 Welch's paper. The cases referred to were reported by nineteen 

 different observers, and the total number treated was 1,489, with 

 a mortality of 14'2 per cent. Of these cases, 222 were treated with 

 the antitoxic serum on the first day of sickness, with a mortality 

 of 2'2 per cent ; 456 cases on the second day, with a mortality of 

 8'1 per cent ; 311 on the third day, with a mortality of 13*5 per 

 cent; 168 on the fourth day, with a mortality of 19 per cent; 116 

 on the fifth day, with a mortality of 2 9 '3 per cent ; 44 on the sixth 

 day, with a mortality of 34*1 per cent ; 104 after the sixth day, 

 with a mortality of 33*7 per cent ; 68 undetermined. 



The time at my disposal will not permit me to dwell longer 

 upon the practical results already attained in preventive medi- 

 cine and in specific therapeutics as a result of bacteriological 

 investigations. But before closing I desire to call attention, as 

 briefly as possible, to the value of the recent additions to our 

 knowledge relating to the causes of disease, in the way of an exact 

 and early diagnosis. In certain infectious diseases such knowl- 

 edge is of great importance, not only in the interest of the pa- 

 tient, but of others liable to infection. This is especially true in 

 diphtheria and in tuberculosis of the lungs. In the first-men- 

 tioned disease an early differentiation of true diphtheria from 

 pseudo-diphtheria is often impossible without resort to methods 

 by which the bacteriologist is able to detect the presence of the 

 diphtheria bacillus. In pulmonary tuberculosis, also, the bacte- 

 riologist can usually detect the tubercle bacillus in the sputa be- 

 fore the clinical expert can recognize with certainty the physical 

 signs of the disease. Scientific physicians in all parts of the 

 world now resort to the use of the microscope and the staining 

 methods by which this bacillus is recognized for making an early 

 diagnosis in cases of this nature. Other diseases in which the 

 recognition of the specific germ establishes the diagnosis are re- 

 lapsing fever, typhoid fever, glanders, and anthrax the two last 



