102 MICHIGAN ACADEMY OF SCIENCE. 



This he incubates at 37$ for four to six hours, when he finds the Eberth 

 bacillus, if present, enormously increased. He suggests the solution be 

 made slightly acid with Parrietti solution. 



The method used in the hygienic laboratory was devised by Doctor 

 Vaughan in 1888, previous to the work of Rodet. 



(1) The water for examination must be sent in sterile bottles. 



(2) Three to four gelatin plates are made from one drop of the water. 



(3) Tubes of beef tea are inoculated with 10, 20 and <>0 drops of water 

 and incubated at 38° to 39° C. for twenty-four hours. 



(4) If no growth occurs the water is pronounced safe as it contains 

 no bacteria capable of growth at body temperature. 



(5) If growth occurs, plates are made from tubes by Koch's method 

 and animals inoculated intra-abdominally with one-half to one c. c. 



(6) Animals dying from inoculations are posted and plates made from 

 abdominal organs. Smears and hanging drop are made. 



1 7) Colonies developing on plates made from water, beef tea and 

 abdominal organs are studied, pure cultures made and bacteria classi- 

 fied. 



(8) If animals are unaffected by inoculations the water can be pro- 

 nounced safe; in case animals die the water is condemned. 



Two groups are made of the germs found: 1. Those resembling the 

 bacillus of Eberth, the typhoid group, and those resembling the Bac- 

 terium coli communis, the colon group. It is only in the method of 

 distinguishing these groups that any change has been made in the 

 original method. 



For their differentiation we rely upon: 1. The coagulation of milk. 

 2. The Indol reaction. 3. The production of acids as shown by litmus 

 gelatin. 



These tests are positive for the colon group, negative for the typhoid 

 group. 



In the coagulation of milk we have one of the best methods for the 

 separation of the typhoid group from the colon group when on the same 

 plates, the appearance of colonies being often so atipical as to be of little 

 value. Twenty or more tubes of sterile milk are inoculated from the 

 colonies and these incubated for twenty-four hours at from 37° to 38°. 

 Tubes not coagulated contain the typhoid group. 



During the past year I have isolated nine bacteria belonging to the 

 colon group, two belonging to the typhoid group, differing in some 

 respects from the bacillus of Eberth, and from one water the bacillus 

 pyocianeus. 



SOME VITAL STATISTICS OF MICHIGAN. 



BY CRESSY L. WILBUR, M. D., LANSING. 

 (Read before the Academy, April 1, 1897.) 



Lord Bacon, the apostle of modern inductive science, "has said: "The 

 true greatness of a state consisteth essentially in population and breed 

 of men." If this aphorism be true, then it must follow that exact 

 knowledge of the character of the population of Michigan and its quan- 



