334 
T. H. GOODSPEED AND R. E. CLAUSEN 
vironmental and especially developmental factors in determining the 
expression of the "corolla complex" in Nicotiana. The extent of the 
data and the nature of the conclusions derived therefrom make it 
seem possible to establish tentative criteria in keeping with which 
flower size investigations, in Nicotiana at least, should be carried on 
and interpreted. In the present report no effort will be made to 
illustrate or to discuss specifically the nature or manner of the inheri- 
tance of flower size in Nicotiana. Further reports in preparation aim 
to take up this question in detail and to discuss it on the basis of the 
various considerations herein to be emphasized. 
II. Experimental Material 
The data presented herewith have to do with measurements on 
the size of flowers produced by : 
1. N. Tahacum var. macrophylla Comes (Setchell, loc. cit. p. 8) 
in the growing season 191 3. This N. Tahacum variety has been grown 
here for 6 years in the pure line and will be referred to under its Uni- 
versity of California Botanical Garden number, U. C. B. G. 22/07. 
2. The Fi hybrid N. Tahacum var. macrophylla (22/07) 9 X N. 
sylvestris (ibid., p. 29) which will be referred to as Fi H38. This 
cross was made by Professor W. A. Setchell in 1911 and the flowers on 
25 Fi hybrid plants were first measured in 1912. These Fi plants 
were cut back early in 1913 and came into full flower during May of 
the same year. Their flowers were measured in large numbers. A 
second sowing of the seed of the original cross was made in 1913 and 
the flowers on 10 plants were measured that season. We have thus 
data upon the flower size of: 12 Fi H38, plants from the fir-st sowing 
of the hybrid seed; 13 Fi H38, plants of 12 Fi Has coming up on their 
own roots; 13 (11) Fi Has, plants from a second sowing of the original 
hybrid seed. 
Thus plant No. i of 13 Fi H38 is plant No. i of 12 Fi H38 growing 
the second year on its own roots, while plant No. i of 13 (11) Fi H38 
cannot be compared directly with any plant of 12 Fi H38 or 13^1 H38, 
although it is genetically of exactly the same constitution. 
3. Fi H137, which is the reciprocal of Fi H38. This cross was made 
in 191 2 and flowers on Fi plants were measured in 1913. 
4. The Fi hybrid produced by crossing Fi of the hybrid N. Tahacum 
''Maryland" (ibid., p. 5) 9 X N. Tahacum ''Cavala" cf with N. 
sylvestris. The garden number of this cross is H44. It was made in 
