PART IV. 



HETEROMORPHY. 



There are certain malformations that have little in 

 common beyond this, that they cannot readily be 

 allocated in either of the great groups proposed by 

 writers on teratology. There are also deformities 

 which, unlike the majority of deviations from the 

 ordinary structure, are absolute and not relative. 

 While the latter are due to an exaggeration, or to an 

 imperfection of development, or, it may be, to a par- 

 tial perversion in organization, the former differ from 

 the normal standard, not merely in degree, but abso- 

 lutely. This is often the case when disease or injury 

 affects the plant; for instance, in the case of galls 

 arising from insect-puncture the structure is rather a 

 new growth altogether, than dependent on mere hy- 

 pertrophy of the original tissues. These absolute 

 deformities arising from the causes just mentioned 

 belong rather to pathology than to teratology strictly 

 so called ; but, under the head of deformities, may be 

 mentioned sundry deviations not elsewhere alluded to. 



CHAPTER I. 



DEFORMITIES. 



The special meaning here attached to the term 

 deformity is sufficiently explained in the preceding 

 paragraph ; it remains to give a few illustrations, and 

 to refer to other headings, such as Hoterotaxy, Hyper- 



