XVI 



LIST OF ILLUSTRATIONS 



85. 

 86. 

 87. 



90. 

 91. 

 92. 



93- 

 94. 



95- 



Diagram of the conjugation of an Infusorian 

 Conjugation of an Infusorian .... 

 Diagram to illustrate the operation of amphimixis 

 Sperm-mother-cells (spermatocytes) of the Salamander 

 Anterior region of the larva of a Midge 

 The Common Shore-Crab, seen from below . 



Hind leg of a Locustid 



Echinoderm-larvaj 



Development of a limb in the pupa of a Ply 



Diagram to illustrate the phylogenetio shifting back of the origins 



of the germ-cells in medusoids and hydroids 



Diagram to illustrate the migration of the germ-cells in Hydromedusse 



3(54, 



PA6E 



321 

 323 

 348 

 350 

 393 

 367 

 371 

 .387 

 395 



412 

 414 



COLOURED PLATES 



SOME MIMETIC BUTTERFLIES AND THEIR IMMUNE MODELS 



Plate 1 - . . . . . to face page 112 



Plate II 114. 



Plate III „ „ 116 



