18 BOTANICAL GAZETTE [january 



O. blandinaXO. rubrinervis. — For this cross I used two speci- 

 mens of 0. blandina of the third generation in 19 13, the one being 

 a pale green and the other a normal color. In 19 14 each of the 

 cultures embraced 60 plants, of which 25 flowered. The percent- 

 ages for blandina were 48 for the green, but only 20 for the pale 

 parent. For this reason I repeated the latter culture in 191 5 and 

 obtained from 70 plants 47 per cent blandina. The types of sub- 

 robusta and velutina in these cultures w r ere exactly the same as those 

 from the reciprocal cross. 



The percentages given are obviously of the same type as those 

 for the splitting into laeta and velutina and come as near to equality 

 for the two types as may be expected under ordinary conditions of 

 cultivation. I propose to grow the second generation next summer. 



The viability of the seeds of O. Lamarckiana mut. velu- 

 tina. — Besides the external differences between our new mutant 

 and the parent species, there is another mark which lends a high 

 interest to the new form. This is found in the seeds. The seeds 

 of O. Lamarckiana differ from those of almost all other species (with 

 the exception of 0. suaveolens) in containing a large proportion of 

 empty grains, even under the most favorable conditions of life. 

 More than one-half of the seeds have no germ at all, although 

 externally they are, as a rule, not distinguished from the normal 

 ones. Renner 10 has studied the development of these empty 

 seeds and found that their germ is fecundated and undergoes one 

 or two cell divisions, but then stops and dies off. He considers this 

 phenomenon as a hereditary character of the species. It runs 

 parallel, in this respect, to the rudimentary ovules described by 

 Geerts, which are characteristic of the whole group of the Oeno- 

 theras. Besides this type of empty seeds a less or larger number 

 usually occur which stop their development at a much later stage. 

 The proportion of these can be diminished by a better culture, 

 and therefore they may be considered as a result of the crowding 

 of the seeds in the capsules, combined with the limited amount of 

 nourishment available for them. 



Our new mutant velutina produces hardly any abortive seeds, 

 at least under normal conditions of culture. I tried the seeds from 



10 Renner, O., Befruchtung und Embryobildung bei Oenothera Lamarckiana. 

 Flora 7:115-150. 1914, 



