CONTENTS 



PART I 



J OF THE ELEMENT ALIST CONCEPTION OF THE 

 ORGANISM 



A. Composition of the Living Individual 



CHAPTER PAOE 



I. INTRODUCTORY . . 1 



Historic hack-ground, 1. Nature and scope of the undertak- 

 ing, 34. 



II. THE OlU.ANISM AND ITS MAJOR PARTS 30 



He fled ions on the problem of individuality in the living world, 

 in. The individual plant and its parts, S3. The individual 

 animal and its parts, 89. 



III. THE ANIMAL ORGANISM AND ITS GERM LAYERS .... 45 



The germ-layers, their role in development, and the germ-layer 

 theory, 40. Are germ-layers developmental organs and subser- 

 vient to the developmental requirements of the organism? Ifi. 

 A negative answer to the question in the last section expected 

 of element ulist biology, 4^. Evidence that germ-layers are 

 Unix xiibxcrrient to the organism, 49: (a) Evidence from bud 

 jn-oi>agation in compound ascidians, 50; (6) Evidence from 

 laid i-o)>a<jation in bryozoa, 53; (c) Evidence from the regen- 

 eration of the lens of the amphUtian eye, 57. The germ-layer 

 theory and the germ-plasm theory, 58. The exact mode of 

 inrolrciiieiit of the germ-plasm theory in the germ-layer 

 theory, 59. Weismann's studies on the origin of germ-cells in 

 hi/droidn, GO. Inconclusiveness of Weismann's results shown 

 by Goette and others, 2. Weismann's erroneous conclusions 

 concerning the origin of sex-cells in hydroids as an example 

 of the effect on the observing powers of the germ-plasm type 

 of speculation. C>6. The strongly organismal implications of 

 conclusions on the origin and migration of germ cells 

 xxiii 



