lS93-] DODGF. BACTERIA AND THE PUBLIC HEALTH. 211 



The foUowin.ij; paper was read : 



BACTERIA AND THE PUBLIC HEALTH. 

 By Professor Charles ^VRIGHT Dodge. 



The lecture, which was popular in its nature, was introduced by 

 a brief glance at the yeast plant, which in its structure and some of 

 its habits bears a general resemblance to bacteria. The morpho- 

 logical and physiological means of classification of bacteria were 

 mentioned, then the various points of structure, the functions of the 

 different parts and the methods of reproduction were discussed. The 

 conditions of life as shown by the relation of bacteria to moisture, 

 air, temperature, food supply and light were reviewed, and mention 

 made of the products of the vital activities of bacteria, e.g., fermen- 

 tation, putrefaction, nitrification, and the formation of gases and 

 pigments, and the exhibition of fluorescence and phosphorescence. 

 Some of the methods by which bacteria are studied were illustrated, 

 and the special apparatus used in bacteriological investigation exhib- 

 ited and explained. The lecturer then passed on to a general 

 discussion of these organisms in their relation to man, taking up 

 briefly the topics of dust and ventilation, water supply, filtration and 

 sewage, clothing, food, social customs, etc., as sources of infection. 

 A hasty glance at certain common diseases as diphtheria, tubercu- 

 losis, typhoid fever and cholera was then made, the reasons given for 

 considering such diseases of bacterial origin ; some of the po-sible 

 sources of infection named, and precautions given to assist in 

 avoiding infection. 



The lecture was illustrated by charts showing the structural 

 features of various forms of bacteria; by a large number of pure 

 cultures on various nutritiv^e media to show characteristic growths ; 

 by mixed cultures made by exposure of culture plates to air, 

 water, etc.; and by cultures made from various foods, and from 

 books, money, clothing, etc., etc. Microscopic preparations of 

 pathogenic and non-pathogenic bacteria, and sections of infected 

 tissue were shown. The various utensils and pieces of apparatus 

 used in a bacteriological laboratory were also exhibited. 



The paper was profusely illustrated by cultures of bacteria, 

 microscopical slides and bacteriological apparatus. 



