XI. PLANTS WITHOUT CHLOROPHYLL IN THEIR 

 RELATION TO MAN 



Problems. (a) How molds and other saprophytic fungi do 

 harm to man. 



(&) What yeasts do for mankind. 



(c) A study of bacteria with reference to 



(1} Conditions favorable and unfavorable to growth. 

 (2} Their relations to mankind. 



(3} Some methods of fighting harmful bacteria and dis- 

 eases caused by them. 



LABORATORY SUGGESTIONS 



Field work. Presence of bracket fungi and chestnut canker. 



Home experiment. Conditions favorable to growth of mold. 



Laboratory demonstration. Growth of mold, structure, drawing. 



Home experiment or laboratory demonstration. Conditions unfavor- 

 able for growth of molds. 



Demonstration. Process of fermentation. 



Microscopic demonstration. Growing yeast cells. Drawing. 



Home experiment. Conditions favorable for growth of yeast. 



Home experiment. Conditions favorable for growth of yeast in bread. 



Demonstration and experiment. Where bacteria may be found. 



Demonstration. Methods of growth of bacteria, pure cultures, and 

 colonies shown. 



Demonstration. Foods preferred by bacteria. 



Demonstration. Conditions favorable for growth of bacteria. 



Demonstration. Conditions unfavorable for growth of bacteria. 



Demonstration by charts, diagrams, etc. The relation of bacteria to 

 disease in a large city. 



To THE TEACHER. In these days when the application of biology to human 

 welfare is so often made the chief aim of a course in biology, it is refreshing to know 

 that there are teachers left who believe in logic and in the building of a super- 

 structure before proceeding to work upon the top of the building. In point of 

 interest and of instructive value, the exercises which follow are vital ; as experi- 

 ments, however, they are not always absolutely to be relied upon. The extreme 

 delicacy with which some of the factors work, the fact that we are dealing with 

 microorganisms which cannot be handled except in bulk, the fact that most school 

 laboratories have neither equipment nor means to obtain some of the necessary 

 materials, make absolutely accurate experiments sometimes out of the question. 



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