IK SETEHAL SPECIES OF THE OESUS LINUM. 73 



not SO surely receive tlieir own pollen as do the long-stjled. The 

 greater self-fertility of the short-styled flowers was, as we have 

 seen, also shown by the plants left to themselves, and but sparingly 

 visited by insects, in the flower-garden in 1861, and likewise by 

 those raised in 1862. 



The absolute sterility (judging from the experiments of 1861, 

 and which is hardly contradicted by those of 1862) of the long- 

 styled plants with their own-form pollen led me to examine into 

 its apparent cause ; and the result is so curious that it will be 

 worth while to give most of the experiments in detail. These ex- 

 periments were tried on fresh plants, grown in pots and brought 

 successively into the house. 



First. I placed pollen from a short-styled flower on the 

 five stigmas of a long-styled plant, and after thirty hours found 

 them deeply penetrated by a multitude of pollen-tubes, far too 

 numerous to be counted ; the stigmas had become discoloured and 

 twisted. I repeated this experiment on another flower, and in 18 

 hours found the stigmas penetrated by a multitude of long pollen- 

 tubes. All this is what might have been expected, as this is a fertile 

 or heteromorphic union. I likewise tried the converse experiment, 

 and placed pollen from a long-styled flower on the stigmas of a 

 short-styled flower, and in 24 hours found the stigmas discoloured, 

 twisted, and penetrated by numerous pollen-tubes ; and this, again, 

 is what might have been expected, as this is a fertile or hetero- 

 morphic union. 



Secondly. I placed pollen of a long-styled flower on all five 

 stigmas of a long-styled flower on a separate plant : after 19 liours 

 I rigorously dissected the stigmas, and found only a single pollen- 

 grain which had emitted a very short tube. To make sure that 

 the poUen was good, I took in this case, and in most other cases, 

 pollen either from actually the same anther or from the same 

 flower, and proved it to be good by placing it on the stigma of a 

 short-styled 'plant, and seeing numerous pollen-tubes emitted. 



Thirdly. Eepeated last experiment, and placed own-form pollen 

 on all five stigmas of a long-styled flower ; and, after 19i hours, 

 not one single grain had emitted its tube. 



Foiirtldy. Eepeated the experiment, with the same result after 

 24 hours. 



FiftJdy. Eepeated last experiment, and, after leaving pollen on 

 for 19 hours, put an additional quantity of own-form poUen on 

 all five stigmas. After an interval of exactly three whole days, 

 I rigorously examined the stigmas, which, instead of being dis- 



LIKN. PEOC. BOTAiry, TOL. Til. O 



