and Laboratory Methods. ^^"1 



After reading Dr. Prudden's books, and after class-room discussions, each 

 pupil was asked to outline at home the arguments in favor of and against the bac- 

 teria. The case is stated thus in one of the papers : 



" Benefits of Bacteria to Mankind. They construct food-stuffs for plants 

 out of the nitrogen gas and the solutions absorbed from the soil. 



" They ripen the cream before churning and thus form butter. 



" They give flavor to butter. 



" They are an absolute necessity in making cheese. 



" In making vinegar from cider, yeast and bacteria work together, 



" Bacteria perform a very necessary work in the process of ' retting ' flax in 

 the linen industry, without which we would not have our fine linen and delicate 

 laces. 



" Bacteria play a prominent part in the curing of tobacco. 



" Sprouting of seeds is promoted by bacteria. 



" Streams and lakes are cleared by bacteria. 



"They decompose dead animals into the dust from whence they came. 



"The Ways Bacteria Prove to be ' Man's Invisible Foes.' Bacteria cause 

 the diseases, consumption, typhoid fever, scarlet fever, pneumonia, leprosy, lock- 

 jaw, influenza, cholera. 



" They cause blood poisoning. 



" They destroy foods." 



The primary aim of these eight lessons in bacteriology, as already stated, 

 was a practical one, namely, to present to the boys and girls of our city a most 

 telling argument for cleanliness in the care of the home and in the care of the 

 city. The colored charts portraying the cases of consumption in the region of 

 Mott street and of diphtheria in the Tenth and Twelfth wards will not soon be 

 forgotten. Hence the New York of to-morrow will doubtless number among 

 its citizens at least a few more staunch supporters of an efficient Board of Health ; 

 a few more homes will probably be free from the danger of disease contagion, 

 and a few more house-wives will exercise greater care to secure abundance of 

 light and of fresh air in their homes and to select and prepare nutritious foods. 



The treatment of the subject, however, was not allowed to leave in the minds 

 of the pupils the lasting impression that we have discovered in bacteria an omni- 

 present and well-nigh omnipotent enemy. They were led to see that consump- 

 tion, cholera, typhoid, and all the other diseases charged to these micro-organ- 

 isms are due to the ignorance or carelessness of man, and that these diseases 

 can be prevented. While, on the other hand, they learned that the bacteria are 

 toiling incessantly to clear our earth from the debris of decay, and to prepare the 

 soil and the air for the growth of the higher plants. Thus this study becomes a 

 part of the great study of biology, and in this fact lies the deeper interest of the 

 subject. In the hay infusion all the functions of living nature are in full oper- 

 ation. There one may study assimilation, oxidation, respiration, excretion, the 

 life and death struggle for food, reproduction, and even something akin to sen- 

 sation ; for who of us, after an hour at the microscope, watching the varying 

 movements in this world of micro-organisms, is prepared to deny absolutely all 

 sentient impressions even among bacteria ? Biological study of this sort should 



