ILLUSTRATIONS xxi 



vox the effect of a galvanic current on the currents of 

 water produced by the flagella 328 



118. Diagrams illustrating the effect of direct current on the dis- 



tribution of ions in colonies of Vol vox and their response 330 



119. The relation between rate of locomotion, gel/sol ratio, and 



hydrogen-ion concentration in a balanced salt solution . 334 



120. The relation between rate of locomotion, gel/sol ratio, 



hydrogen-ion concentration, and sodium-ion concentra- 

 tion 335 



121. The relation between rate of locomotion, gel/sol ratio, hydro- 



gen-ion concentration, and calcium-ion concentration . . 336 



122. The effect of adding calcium in different concentrations to 



0.005 N sodium solutions, on the relation between hydro- 

 gen-ion concentration, rate of locomotion, and gel/sol 

 ratio 337 



123. Capillary tube used for the sterilization of Trichomonas 



hominh 456 



124. Migration tube 459 



125. V migration tube for semisolid media 460 



126. Migration-dilution apparatus drawn to show construction 462 



127. Details of construction of the sponge-and-glass plunger for 



the collection of cysts 465 



128. Growth phases in a hypothetical population 494 



129. Hypothetical modifications of the normal growth of a popu- 



lation, from the initial stationary to the maximal stationary 

 phase 496 



130. Growth in length and in area of 'Paramecium caudatum . . 521 



131. Growth in breadth and thickness of Paramecium caudatum 522 



132. Growth in volume of Paramecium., Frontonia, and Hartman- 



ella 524 



133. Hypothetical curves to illustrate phases of population growth 546 



134. Population growth curves of Euglena, Paramecium, Siylo- 



nychia, and Mayorella 549 



135. Diagram of the life cycle of Trichomonas augusta .... 570 



136. Diagram of the life cycle of Endamoeha coli {Councilmania 



lafleuri) 572 



