INTRODUCTION. 
9 
It is ufeful to know this perfectly, not only with that higher pur- 
pofe, but for the leffer ufes alfo of an artificial method : for without 
thefe objects of the natural gradation, the characters of this artificial 
diftinCtion would never be fo deeply fixed in the fludent’s memory ; nor 
are they fo perfectly neceffary in any other place ; fince, for want of a 
precife determination of them, or of an accurate attention to them, this 
very natural Clafs has been Itrangely torn and divided ; and a great 
many Plants truly belonging to it, have been thrown into others. 
Thus the Eryngimand Aftrantia, the Hydrocotyle and Echinophora, 
have been called Umbelliferous Plants, though wanting the true and 
only di&inCtive charader of that alfo natural Clafs ; and perfectly 
agreeing in every article of the diftinCtions of this. The common 
Thrift might as juftly be called an Umbelliferous Plant as any of thefe ; 
and by a very little lengthening of the Footftalks of its feparate Flowers, 
would be as well entitled to the character as any of them. But nei- 
ther are they Umbelliferous Plants, according to the true character of 
that perfectly natural arrangement ; neither could Thrift, by lengthening 
the Footftalks of its Flowers, be made onej if that were the cafe, the 
union of the fix Claffes would not exifl ; and nature would be more 
like art by far than God has made her. 
The connection between the four Affembled Claffes and the Um- 
belliferous, is not to be fought from the Tubulate kind, as we have 
feen, for there want three of the four gradations j and therefore the 
Plants, which fhould in that way conneCt the two Claffes, are not at 
equal diftance from both : but taking the Aggregate, we fee the exaCt 
proportion. The Affociate Clafs alfo makes an advance between the 
three firft, and this fifth. Its Floret opening into longer fegments, and 
its Chives, though they Hand near, not being united. 
The length of Footftalk to the Flower, though an accidental 
and uncertain mark, yet is the ftriking^and obvious character by which 
the Aggregates differ from the Affociates one way, and from the Um- 
belliferous Plants the other : let us fee the confequence of giving more 
or lefs to this part. 
B 
Shorten 
