180 



Mil. 0. BAEWIN ON" TUB SEXUAL HEIATIONS OF 



the more fertile 'imions ; but it rendered the less fertile imions 

 even more sterile than they otherwise would have been. I have 

 seen striking instances of this same fact in making homomorphie 

 and heteromorphic unions in Primula * ; and it is well known 

 that the conditions of life must be highly favourable to give any 

 chance of producing hybrids from species which cross with diiB- 

 culty. 



Table I. — LoNG-STiiED Fosm. 



I. 



13 flowers fertilized hy the longer 

 stamens of the mid-styled. T/iese 

 damms equal in length the pistil of 

 the loiig-styhd. 



Product of good seed in each capsule. 

 36 53 



81 















— 



45 

 41 

 38 per cent, of these flowers yield- 

 ed capsYiles. Each capsule contain- 

 ed, on an average, 51-2 seed. 



II. 



13 flowers fertilized by the longer 

 stamens of the short-styled. These 

 stamens equal in length the pistil of 

 the long-styled. 



Product of good seed in each capsule. 

 159 104 



43 119 



96 poor seed. 96 

 103 

 

 



99 

 131 

 116 



114 



84 per cent, of these flowers yield- 

 ed capsules. Each capsule con- 

 tained, on an average, 107'3 seed. 



* In the spring of 1862 I crossed forty Cowslip flowers {P. veris) hetero- 

 morphieally and homomorphicaUy. The plants were accideutaUy exposed in 

 the greenhouse to too hot a sun, and a numher of umbels perished. Some, 

 however, remained in moderately good health, and on these there were twelve 

 flowers which had been fertflized hotcromorphically and eleven which had been 

 fertiliised homomorphicaUy. The twelve heteromorpliio miions yielded seven fine 

 capsules, containing on an average 57'3 good seed. Now mark the difference : 

 the eleven homomorphie unions yielded only two capsules, of which one con- 

 tained 39 seeds, but so poor, that I do not suppose one would have germinated, 

 and the other only 17 fairly good seed. It would be superiluous to give any 

 more details on this experiment, or on some which I made at the same time on 

 P. Sinensis, after the appearance of Mr. John Scott's admirable paper on the 

 various dimorphic species of Primula, in which he confirms my former results, 

 and adds many original and valuable observations. Dr. Hddebrand has also 

 (Botanischo Zeitung, 1864, Jan. 1, S. 3) confirmed my general residts with respect 

 to P. Sinensis, and has corrected an error into which in some unaccountable 

 manner I feU, namely, that the poflen-grains from the long- and short-styled 

 forms -were of the same size. Dr. Ilildebrand has added a series of new and 

 important experiments, for he fertflized homomorphicaUy a number of flowers 

 with poUen from the same form, and likewise from the same individual flower. 

 These latter he found were thus rendered rather more sterfle. This experiment, 

 I believe, has never been systematically tried before. 



