Contents xxvii 



CHAPTER PAGE 



mentalism, 305. This due particularly to discovery of inler- 

 dependence between adult characters and chromosomes of 

 yerm-cells, 306. Revised conception of heredity essential to 

 interpreting this interdependence, 307. Unwarrantable tend- 

 ency to restrict heredity to sexual propagation, 308. Unwar- 

 rantable tendency to restrict heredity to adult characters, 311. 

 Importance of recognizing heredity as icorking by transforma- 

 tion rather than by transmission, 312. Tendency to confuse 

 heredity with causes of heredity, 313. Definition of heredity 

 adopted in this discussion, with remarks on its application to 

 the chromosome theory, 31/f. Meaning and criterion of "mech- 

 anism of heredity," 323. 



XII. Evidence Favorable to CiiRo^rATix as Hekeditary Sub- 



stance 326 



A. Direct Evidence. Eindence from the ontogeny of some 

 protozoans, 326. Evidence from, certain cells of multicellular 

 organisms, 331. Evidence from spermatozoan, 333. Evidence 

 from pigment cells, 333. B. Indirect Evidence, 341. The 

 chromosomes of germ-cells in fertilization, 342. Fertilization 

 of the ova of one species by the sperm of another species, 344- 

 The connection of sex with a particular chromosome, 846. The 

 connection of mutations with particidar chromosomes, 853. 

 Chromosomes and the Mendelian mode of inheritance, 856. • 



XIII. Evidence from Protozoans That Substances Other Than 



Chromatin Are Physical Bases of Heredity . . . 362 

 Evidence from, the ontogeny of various protozoans, 363: {a) 

 Stentor, 363; (b) What study of the ontogeny of Diploditiium 

 will probably discover, 370; (c) T'he origin of flagella, 370; 

 (d) Various organs of Stylonychia and Paramecium, 373; (e) 

 The skeleton of radiolaria, 375; (/") Openings in the central 

 capstde of the radiolaria, 379; (g) The shells of foraminifera, 

 385; (h) The clinging organs of sporozoa, 386; (i) The "di- 

 vision center'^ of NoctHuca, 390; (j) The centrosphere of pro- 

 tozoa generally, 394. Concluding remark on the evidence pre- 

 sented, 397. 



