IN SEVERAL SPECIES OF THE GENUS LINUM. 78 
not so surely receive their own pollen as do the long-styled. 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 contradieted 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. Y 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. Allthisis what might have been expected, as this is a fertile 
or heteromorphie 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 hours 
I rigorously dissected the stigmas, and found only a single pollen- 
grain which had emitted a very short tube. To make sure that 
the pollen 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. Repeated last experiment, and placed own-form pollen 
on all five stigmas of a long-styled flower ; and, after 193 hours, 
not one single grain had emitted its tube. 
Fourthly. Repeated the experiment, with the same result after 
24 hours. 
Fifthly. Repeated last experiment, and, after leaving pollen on 
for 19 hours, put an additional quantity of own-form pollen on 
all five stigmas. After an interval of exactly three whole days, 
I rigorously examined the stigmas, which, instead of being dis- 
LINN. PROC.—BOTANY, VOL. VII. G 
