LIST OF ILLUSTRATIONS XXvii 



95. Herpetomonas musca-domestica 134 



96. Trypanosoma tincce and Trypansoma perccB 135 



97. Trichomonas eberthi 136 



98. Lamblia intestinalis 137 



99. Development of sporozoits in Laverania malaria 138 



100. Solutions, diagrammatic 157 



101. Movement of electric current and ionization 159 



102. Apparatus employed in determination of H-Ion concentration 166 



103. Illustrating surface forces 169 



104. Illustrating surface pull 170 



105. Particle in Brownian motion 172 



106. Plasmolysis in cells 177 



107. An arrangement of dispersoids 181 



108. Comparison of particles of different size 182 



109. Ultramicroscope 183 



no. Illustrating cell activities 196 



in. Amoeba proteus 197 



112. Influence of oxygen on microorganisms 229 



113. Crystals of bacteriopurpurin 247 



114. Carbon cycle '....' 259 



115. Nitrogen cycle 260 



116. Sulphur cycle 261 



117. Action of light on bacteria 278 



1 1 8. Action of light on molds 279 



119. Action of light on mold colonies 280 



120. Chemotaxis 286 



121. Curve of disinfection 289 



122. Influence of filtered water on typhoid fever and Asiatic cholera 315 



123. Section of sand filter 323 



124. Unglazed porcelain filters 325 



125. 126, 127. Location of wells on farm 327 



128. Construction of model well 328 



129. Trickling filter, sand filter, dosing tank, septic tank 341 



130. Septic tank 342 



131. Non-symbiotic nitrogen-fixing organism (B. pastciirianns) 402 



132. Non-symbiotic nitrogen-fixing organism (A zotobacter vinelandi] 403 



133. Ps. radicicola 407 



134. Section through root tubercle 408 



i-SS* T 36, 137. Influence of Ps. radicicola 411,412,413 



138. Section of cow's udder 434 



139. Bacterial colonies in dust from udder 437 



140. Bacterial colonies from cow's hair 438 



141. Bacterial colonies from dust of stable 439 



142. Small-top milk pails 442 



143. Ropy cream 464 



144. Ropy cream organisms 465 



145. Chart of Rochester milk supply 469 



146. Gassy cheese 488 



147. Cheese from lactic starter 489 



148. Influence of lactic organisms on casein degradation 495 



149. Swiss cheese 500 



150. Kefir grain 509 



151. Chart. Effect of storage on bacterial content of ice cream 514 



152. Chart. Influence of temperature on sterilizing time 537 



153. Chart. Influence of number of spores on sterilizing time 537 



154. Chart. Influence of speed of rotation on heat penetration. 538 



155. Tubes for feces examination 602 



