XXX INTRODUCTION. 



of the several cases of malformation given in these 

 pages are generally arranged according to their appa- 

 rent degree of importance. Thus, in a case of prolifi- 

 cation associated with multiplication of the petals, the 

 former change is a greater deviation from the customary- 

 form than the latter, hence reference should be made, 

 in the first instance, to the sections treating on prolifi- 

 cation, and afterwards to those on multiplication. To 

 facilitate such research, numerous cross references are 

 supplied. 



In the investigation of teratological phenomena con- 

 stant reference must be made to the normal condition, 

 and vice versd^ else neither the one nor the other 

 can be thoroughly understood. It cannot, however, be 

 overlooked that the form and arrangement called nor- 

 mal are often merely those which are the most common, 

 while the abnormal or unusual arrangement is often 

 more in consonance with that considered to be typical 

 than the ordinary one. Thus, too, it is often found 

 that the structural arrangements, which in one flower 

 are normal, are in another abnormal, in so far that 

 they are not usual in that particular instance. 



For purposes of reference, a standard of comparison 

 is required ; and this standard, so long as its nature is 

 not overlooked, may, indeed must be, to some extent, 

 an arbitrary one. Thus in the phanerogamous plants 

 there is assumed to exist, in all cases, an axis (stem, 

 branches, roots, thalamus, &c.), bearing leaves and 

 flowers. These latter consist of four whorls, calyx, 

 corolla, stamens, and pistils, each whorl consisting 

 of so many separate pieces in determinate position 

 and numbers, and of regular proportionate size. 

 A very close approach to such a flower occurs 



