CONTENTS xiii 
2. In Crosses between Species . ..... : 188 
3. In. Mutant Races. . by ee PE ek 193 
4. In Tetraploid Races . 194 
Identity of Distribution of the Si-chrbriosomis and oF Gexdinked 
Factors . : ar 195 
1. In Ordinary Greases bia, ‘@acweidlise!2iaws 195 
2. In Cases of Non-disjunction. == 8 ...... . 196 
CHAPTER VIII 
MULTIPLE ALLELOMORPHS 
Definition of Multiple Allelomorphs.............. 202 
Examples of Multiple Allelomorphs . 202 
The Alternative Interpretations of Identical Loci and Complete 
Linkage. er ie ok” MR ge 204 
CHAPTER IX 
MULTIPLE’ FACTORS , 
The Meaning of the Term “Multiple Factors” ssa yl 219 
Examples of Multiple Factor bee ES Bee AS Se Rs 219 
Selection and Multiple Factors ep ey tah 248 
CHAPTER X 
THE FACTORIAL HYPOTHESIS 
On the Relation between Factors and Characters . .... 262 
1. The Organism-as-a-Whole Objection : 265 
2. The Invariability of the Factor and the Variability i in the 
Character : a ae 266 
3. So-called Contamination of Allelomorphs 268 
4. Fractionation. 268 
5. The Presence and Aoscuue Higpothiesis : 270 
Weismann’s Preformation Hypothesis and the Factorial Theory . 277 
CHAPTER XI 
VARIATION IN THE PROTOZOA 
Fission Lines ©. «1.2... eee eee 2» » 282 
Change in Number of Nuclei ee Pas aa SE 2a a « 291 
