AAA, ENATION. 
nature of these bodies, in the absence of a knowledge of 
their period and mode of formation. They may be mere 
outgrowths from one or other of the customary whorls, 
or they may represent abortive stamens or petals, &c. 
Where circumstances prevent the course of develop- 
ment from being traced, something may be inferred as 
to their real nature from their position in regard to the 
other parts of the flower, from their anatomical struc- 
ture, and from analogy or comparison with like organs 
in other plants. The period of their formation is, 
perhaps, of less importance than was at one time sup- 
posed, since it is well ascertained that, in some cases, 
the formation of the parts of the flower, e.g. the sta- 
mens of mallows, follows a centrifugal rather than a 
centripetal order. 
In the case of monstrous developments of this nature 
too much care can hardly be exercised, and the observer 
should rarely venture on an explanation of the nature 
of the case from the evidence afforded by the monstrous 
erowth apart from that to be derived from the study 
of the development and organization of the normal 
flower and from analogous formations in allied plants. 
Excrescences from axile organs—Warts—In a preceding 
paragraph the formation of enaurs has been alluded 
to. There are other outgrowths, called warts, occasion- 
ally met with in trees, and which are more closely con- 
nected with the central tissues of the stem, while at 
the same time they are not provided with buds, in ~ 
which two particulars warts differ from gnaurs. 
Excrescences of this kind often attain a very large 
size, and may be seen on old elms and other trees, but, 
as their formation is probably more pathological than 
teratological, no further notice of these structures 
need here be given. No special notice need here be 
taken of the tubercles on the roots of so many Legu- 
minose, nor of the peculiar excrescences on the roots 
of Taxodiuwm distichum, as these appear to be normal 
formations. But it may be well to mention im this 
