1^13] Goodspeed: Nicotiana Hyhrids 193 



The first evidence that considerably less than absolute ster- 

 ility can be claimed for certain of the F^ hybrids from crosses 

 of .Y. sylvestris with X. To &ac wm-varieties was connected with the 

 finding of a large number of entirely dry, brown, persisting seed 

 capsules on the plants of cross H38. Six hundred and fifty of 

 these capsules have been collected and more than an equal num- 

 ber remain on the 25 plants representing this cross. From a 

 similar number of plants of the cross H36, 85 capsules have been 

 taken. The plants grown in 1911 from the seed of the 1910 

 crosses have come up from their roots this year (1912) to make 

 fairly vigorous plants and from one plant each of the cross and 

 its reciprocal between 25 and 30 capsules have been taken. One 

 hundred capsules of the 650 mentioned above have been found 

 to contain nearly 900 perfectly formed seeds. A certain propor- 

 tion of them undoubtedly are mere shells and contain no embryo 

 (cf. East and Hayes, p. 30). One hundred of these seeds were 

 arranged as noted in a previous report (Goodspeed, loc. cit., 

 p. 97) and germinated for five weeks under fairly well con- 

 trolled conditions with the temperature approximately 21° C. At 

 the end of this time 26 per cent had germinated, 90 per cent 

 of which germination had taken place in 15 days with the first 

 signs of germination noted at the end of three days. Five seed- 

 lings were allowed to develop and at the end of five weeks are 

 normal in every respect and are considerably past the stage 

 durins: which highest mortality of tobacco seedlings is usually 

 expected. Four hundred of the remaining 550 seeds of this lot 

 are being germinated under the same conditions and at the end 

 of one week almost 25 per cent have germinated. The 1912 seed 

 of H33 and its reciprocal have germinated to the extent of 17 

 per cent and 18 per cent respectively and a number of seedlings 

 nearly four weeks old are developing normally. The brown, dry 

 capsules examined were always much shrunken and withered. 

 They were cut transversely and a brush was forced into the ap- 

 parently empty spaces between the placentae and the wall of 

 the matured ovary. When this operation is carried out over a 

 rough, white surface under a strong light and the ])rush gently 

 rubbed between the fingers any seeds that may have been taken 

 uj) by tlic bi-nsh will fall on to the white surface and can be 



