182 ESSAYS. 
prefoliation, are used in the same sense, and so are not at all 
peculiar to <stivation or prefloration. The like may be said 
of a remaining mode, which belongs, however, tosa different 
category, that in which the parts being united into a tube or 
cup, this is bodily plaited into folds, or otherwise disposed ; 
in which case the margin of the tube or cup, or such lobes as 
it may have, may exhibit any of the modes of zstivation above 
indicated. 
Without further notice, then, of this last, the plicate or 
plaited zstivation, and of analogous conformations of the tube 
or cup of a calyx or corolla, or of the disposition of each piece 
individually (whether revolute, involute, reflexed, inflexed, 
and the like), about the terminology of which there is no 
question, — omitting, likewise, for the latter reason, the case 
of open estivation, — there are left three types to deal with: 
I. With some pieces of the set wholly exterior in the bud 
to others. 
Il. With each piece covered at one margin, and covering 
by the other. 
Ill. With each piece squarely abutting against its neigh- 
bors on either side, without overlapping. 
In modes II and III, the pieces are all on the same level 
and are to be viewed as members of a whorl. In mode I, al- 
though they may sometimes be members of a whorl, some 
parts of which have become external to others in the course 
of growth, they may, and in many cases must belong either to 
two or more successive whorls (as in the corolla of Papa- 
veracece, and even the calyx of Cruciferce, the upper or inner 
of course covered by the lower or outer), or to the spiral 
phyllotaxy of alternate leaves. 
The type of the latter, and the common disposition when 
the parts are five, is with two pieces exterior, the third ex- 
terior by one edge and interior by the other, and two wholly 
interior. This is simply a eycle in ? phyllotaxy, the third 
piece being necessarily within and covered at one margin by 
the first, while it is exterior to and with its other margin 
covers the fifth, this and the fourth being of course wholly in- 
terior. So, likewise, when the parts are three, one exterior, 
