8 CONTENTS 



PEOBLEM PAGE 



90. What is fermentation and what causes it ? 113 



91. To learn to recognize yeast phmts under the compound microscope . 114 



92. Do yeasts grow wild ? 11,5 



93. To determine the conditions favorable to the growth of yeast . . 115 



94. AVhat are the conditions favorable for the growth of yeast in bread ? 



(Homework) . . . 116 



95. How we proceed to the study of bacteria 116 



96. How to prepare culture media ,.117 



97. To demonstrate a pure culture 118 



98. To determine where bacteria may be found 118 



99. To study how rapidly bacteria grow . . . . . . .119 



100. What foods are preferred by bacteria ?....., 120 



101. What effect has heat upon the growth of bacteria ? . . . . 120 



102. To note the effect of moisture and dryness upon the growth of bacteria 



(Home problem) .......... 121 



103. To determine the effect of pasteurization upon the keeping quality of 



milk 121 



104. How to care for milk bottles at home ....... 122 



105. To determine the bacterial content of milk ..... 122 



106. To determine some of the most effective preservatives . . . 123 



107. To determine the most effective disinfectants ..... 124 



XII. The Relations of Plants to Animals . . 127 



108. To study some biological relations of plants and animals in a balanced 



aquarium . .......... 127 



109. To learn what we mean by the carbon and the oxygen cycles . . 128 



110. To find out the course of nitrogen in its relation to plants and animals 129 



111. To prove a hay infusion is an unbalanced aquarium .... 129 



XIII. Single-celled Animals Considered as Organisms 



112. To study a one-celled animal in order to understand better (a) its 



reactions to stimuli ; (6) the cell as a unit of structure 

 113. Comparative study of various forms of single-celled animals to explain 

 division of labor (Extra problem) ..... 



115. To compare reproduction in plants with that in animals 



116. To study the division of labor in tissues and organs . 



117. To find some of the functions common to all animals . 



118. How to know some types of animals in the animal kingdom 



132 

 1.32 



1.35 



XIV. Division OF Labor. The Various Forms of Plants and Animals 137 

 114. How the plant kingdom is classified ...... 



137 

 139 

 140 

 141 

 141 



146 



XV. The Economic Importance of Anijials 



119. What Rnimal foods are cheapest in any locality and why ? (Home 



work) 147 



