CONTENTS 
PAGE 
Introduction 5 
De Vries's studies of Antirrhinum 7 
Correns's studies of Mirdbilis 8 
Results of experiments with maize. 
F x from red, striped, and white seeds of variegated P x 9 
F 2 and F 3 from red-eared F x plants 17 
Non-inherited somatic variations 20 
Interpretation of results. 
Hypothesis of genetic-factor modifications in relation to the in- 
heritance of somatic variations 21 
-Factorial analysis of results with maize. 
P x and F t generations 23 
F 2 and F 3 generations 26 
Comparison of results from Mirabilis, Antirrhinum and Zea 28 
General considerations. 
Factor modifications and heterozygosis 30 
Factor modifications at different stages in the development of the 
plant : 32 
Nature of variegation-factors 33 
Summary 34 
