8 List of Illustrations 



F10CRB PA<SB 



24a. PARTS OF FIVE HEREDITARILY DIVERSE BRANCHES OF A SINGLE 



FAMILY IN DIFFLUGIA CORONA 74 



24b. PARTS OF FIVE HEREDITARILY DIVERSE BRANCHES OF A SINGLE 



FAMILY IN DIFFLUGIA CORONA . 75 



25. THE INFUSORIAN STYLONYCHIA 81 



26. ARCELLA VULGARIS 83 



27. TRYPANOSOMA BRUCEI 97 



28. ORGANISMS USED IN DALLJNGER'S EXPERIMENTS ON THE EFFECTS 



OF HIGH TEMPERATURES 98 



29. CHROMOSOMES AND THEIR MATING 108 



80. DIAGRAM SHOWING THE CHIEF PROCESSES IN THE CONJUGATION OF 



PARAMECIUM CAUDATUM Ill 



31. DIFFERENCES BETWEEN THE CHROMOSOMES OF THE NUCLEI IN THE 

 Two SEXES 115 



32. THE ACTIVE AND PASSIVE PORTIONS OF CELL AND NUCLEUS IN THE 

 EGG OF THE WHITEFISH 117 



33. BEGINNING OF CONJUGATION IN EPISTYLIS 121 



34. SUCCESSIVE STEPS IN THE PROCESS OF CONJUGATION IN VORTICELLA 

 NEBULJFERA 121 



35. DIAGRAMS OF THE MICRONUCLEAR PROCESSES IN CONJUGATION, IN 

 PAHAMECIUM AND VORTICELLA 122 



36. MATING IN THE MOULD, MUCOR 123 



37. MATING OF SIMILAR CELLS, FROM THE ALGA STEPHANOSPH.ERA . 126 



38. CHILODON 129 



39. CONJUGATION OF CHILODON 129 



40. THE EXCHANGE OF THE HALF NUCLEI m PARAMECIUM CAUDATUM 131 



41. MATING OF Two HALVES OF THE NUCLEUS OF SAME CELL . . 134 



42. Two METHODS OF CONJUGATION m SPIROGYRA 135 



43. PROCESS OF CONJUGATION OF Two BRANCHES OF THE SAME PLANT. 136 

 43a. BlPARENTAL INHERITANCE AND THE PRODUCTION OF DIVERSITY BY 



CONJUGATION, IN CHLAMYDOMONAS 156 



44. A FAMILY OF PARAMECIUM CAUDATUM, DESCENDED FROM AN Ex- 



CONJUGANT, AND SHOWING HEREDITARY ABNORMALITIES . . . 160 



45. THE SEPARATION OF THE Two GROUPS OF PAIRED CHROMOSOMES 

 INTO DIFFERENT GERM CELLS, IN THE INSECT NEZARA HILARIS. . 172 



46. THB CHROMOSOMES, AND THEIR SEPARATION INTO Two NUCLEI 

 WITH REDUCED NUMBERS IN THE PROTOZOAN MONOCYSTIS ROSTRATA 176 



