1912] Goodspeed: Nicotiana Hybrids 101 



V. DEVELOPMENT OF SEEDLINGS 



1. Early Development of Seedlings 



Since there was space available for growing only 230 plants 

 of the hybrid N. Tahacum var. macrophylla $X ^- Tahacum var. 

 virginica J', twenty-five of the developing seedlings only of each 

 weight of seed were retained. Each group of twenty-five, with 

 the exception of numbers 1 and 2, from which only ten plants 

 were available, was composed in practically every case of seed- 

 lings of all ages, i.e., those developed from seed which had ger- 

 minated in the germinating case and those produced from seed 

 which had germinated after April 1 in the propagating house. 



The groAvth and early development of all the seedlings was, 

 in general, normal and corresponding in every way. As the 

 seedlings were passing into the typical semi-rosette stage, it 

 was observed that the plants grown from heavy seed were de- 

 veloping more rapidly than those grown from the light seed, 

 though these last had in general germinated a month earlier. 

 This difference in size and general development on May 18 is 

 shown in plate 34, figure 1. As can be seen, the difference in 

 size of the two groups of plants was mainly due to retarded 

 development of the plants from the light seed or, on the other 

 hand, to abnormally rapid growth of the plants from the heavy 

 seed, and was not to any great extent due to a weak or sickly 

 condition of the former. 



2. Number and Condition of Plants in the Field 



The plants were set out in the field early in July. They were 

 placed in two long rows of approximately 110 plants each, with 

 the plants 3i/> ft. apart in the rows and with ten plants repre- 

 senting each number given in the table of the various weights 

 of the seed. Tlic following table gives the number of normal 

 and vigorous plants growing in the field when first carefully 

 examined on September 2 : 



