FORMATION OF SEEDS. 
Both seeds 
and pollen 
formed out of 
their cases. 
No seeds in 
the top root. 
One year’s 
growth of a 
tree. 
then the pollen is seen separating, and running through the 
pith into each flower, and thus attaining the stamen, as the 
seeds do through the alburnum ; but the filling the stamen cases 
is always the last process. Thus both seeds and pollen are formed 
out of their cases, and yet they will all rise together to the deve- 
lopement of the flower, with the same admirable precision. It 
is only watching year after year, and continual dissections, that 
could have thus by degrees enabled me to discover every part of 
this complicated formation , but the many thousands of plants I 
have investigated this year only , and the excessive labour I have 
gone through, did, perhaps, merit some recompence, and I am 
most thoroughly repaid by the certainty of the acknowledged 
fact. 
In trees I have not yet been able to trace the seeds lower 
than in the root, and not, as in herbaceous plants, in the strings. 
I showed in a former letter, that in the under part of the root of 
trees, a quantity of alburnum was laid up for future nourish- 
ment ; but the seeds are found in one line only of this matter. 
I have never yet been able to trace them in the top root j in- 
deed, if ever found there, it is difficult to catch the proper mo- 
ment of seeing them ; because, when the sap is quite liquid, it 
escapes, and the seeds with it, and it is only when it begins to 
form a jelly round the remaining seeds, that they can be tho- 
roughly discerned and examined. But, in herbaceous plants, 
indeed in all that rise each year from the earth, the seeds are to 
be found at most times, and exhibit themselves in so very con- 
spicuous a manner, that no person who will seek them can 
doubt their identity. 
In order perfectly to explain the process, (though I cannot 
do it without some repetitions Tecounted in former letters,) yet 
I will venture, for the thorough elucidation of the whole, to 
give a complete history of the formation and progress of a tree 
for one year, and as in this respect there are but two sorts of 
growth, the stem that does not lie down in the winter, and the 
stem that does j and that the former embraces trees, shrubs, and 
semi-shrubs j and the latter, all plants that rise each year from 
the earth. By giving the life of a tree for one year, and that of 
an herbaceous plant for the same time, I shall show, in a small 
compass, the whole progress of botanical vegetation. The first 
process in a tree is the formation of the flower bud on the line 
of 
