204, Mr. Knight’s Experiments , See. 
genus and species ; and it therefore appears to me, (as vegetable 
mules certainly are not common,) that nature has not per- 
mitted them to exist at all. 
I cannot dismiss this subject, without expressing my regret, 
that those who have made the science of botany their study, 
should have considered the improvement of those vegetables 
which, in their cultivated state, afford the largest portion of 
subsistence to mankind and other animals, as little connected 
with the object of their pursuit. Hence it has happened, that 
whilst much attention has been paid to the improvement of 
every species of useful animal, the most valuable esculent plants 
have been almost wholly neglected. But, when the extent of 
the benefit which would arise to the agriculture of the country, 
from the possession of varieties of plants which, with the same 
extent of soil and labour, would afford even a small increase of 
produce, is considered, this subject appears of no inconsiderable 
importance. The improvement of animals is attended with 
much expence, and the improved kinds necessarily extend them- 
selves slowly ; but a single bushel of improved wheat or peas, 
may in ten years be made to afford seed enough to supply the 
whole island; and a single apple, or other fruit-tree, may within 
the same time be extended to every garden in it. These consi- 
derations have been the cause of my addressing the foregoing 
observations to you at this time ; for it was much my wish to 
have ascertained, before I wrote to you, whether in any instance 
a single plant can be the offspring of two male parents. The 
decision of that question must of necessity have occupied two 
years, and must therefore be left to the test of future experi- 
ment. 
