Contents xxv 



CHAPTER PAGE 



stances, 133: (a) Cyfojjlasni and karyoplasni cliff ereiitiated 

 areas of a common ba.sic substance, 135; (b) Details of cyto- 

 plasmic structure, 137; (c) lliree mxiin theories of the struc- 

 ture of 'protoplasm,, 138; (d) "No universal formula for proto- 

 plasmic structure," 139. Preliminary remarks on the bearing 

 of physical chemistry on the protojjlasm doctrine, I40. Ex- 

 perimental evidence for the specificity of protoplasms, 1/^3: 

 (a) Greater fusibility between closely related species as in 

 tissue mixtures and grafts, lJf3; (b) Protoplasms and not 

 protojylasm must be the form of the protoplasmic conception, 

 148. 



VI. The Organism and its Cei,t.s 150 



What the cell-theory is, viewed historically and substantively, 

 150: (a) Importance and general character of the theory, 

 150; (b) Various forms of the theory as currently held, 150; 



(c) Statement of the theory justified by present state of 

 knowledge, 154- Certain inadequacies of the cell-theory, 158: 

 (a) As tested by embryonic development, 158; (b) As tested 

 by isolated cells and tissues, 167. 



VII. The Cell-theory not Sufficient for Explaining the Or- 



GANIS3I 179 



More general inadeqiuicy of the cell-theory, 179: (a) As 

 tested by the regeneration and restitution of mutilated organ- 

 isms, 179; (b) As tested by the principle of aggregation, 182. 

 (c) As tested by the specificity and metaplasy of differen- 

 tiated cells, 186. Summary of examination of inadequacy of 

 cell-theory, 190. Advance t&ivard the organismal standpoint 

 through conception of cell reached by biochemistry p^ursued in 

 accordance loith the principles of physical chemistry, 191. 



VIII. Further Exa3iination of the Cell-Theory . . . 198 

 The mosaic theory, 198. What the mosaic theory is, 198; A 

 modicum of truth in the mosaic theory, 198. The theory of 

 totipotence, 202. Experimental facts on ichich the theory 

 rests, 202. Balancing the account between the mosaic and 

 totipotence theories, 206. The "promorphology" of germ cells, 

 211: (a) Facts of immediate observation on which the coTir- 

 ception rests, 212; (6) Grounds for believing minute observ- 

 able specific differences between germ cells important, 214; 



