1912] Goodspeed: Nicotiana Hyhrids 117 



PAKT II 



QUANTITATIVE EXPRESSION OF IMPERFECT DOMIN- 

 ANCE IN THE COROLLA DIAMETERS OF THE 

 FLOWERS ON THE HYBRIDS PRODUCED 

 FROM THREE VARIETIES OF NICO- 

 TIANA ACVMIN ATA (Grab.) Hook. 



CONTENTS 



PAGE 



I. Introduction 118 



II. Discussion of the experimental material 119 



(1) Description of experimental material 119 



(2) Basis of identification of our experimental material and 



description of a wild form of N. acuminata 119 



(3) Growing conditions — soil and climatic conditions 123 



(4) Description of tlie Nicotiana flower 125 



III. Technique and methods 126 



(1) Obtaining "pure" seed 126 



(2) Cross pollination 127 



(3) Cleaning of the seed 129 



(4) Sowing of the seed 131 



IV. Experimental work— 1910 132 



(1) General habit of the parental types 132 



(2) Distinctions in corolla diameter and measurements of 



the same 133 



(3) Cross pollinations made between parents 135 



V. Experimental work — 1911 136 



(1) Cleaning, sowing, and germinating of the 1910 seed 136 



(2) Number and condition of the plants in the field 137 



(3) General habit of the hybrid plants 137 



(4) Method of measuring corolla diameter 138 



(5) Results of the measurements 139 



VI. Summary of results 144 



VII. Discussion of results 145 



VIII. Literature cited 152 



IX. Explanation of plates 158 



