444 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 

 growth 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 gnaurs ' 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- 

 minosce., nor of the peculiar excrescences on the roots 

 of Taxod'mm distichum^ as these appear to be normal 

 formations. But it may be well to mention m tin's 



