17 



composition, and properties," being alike subject to heredi- 

 tary transmission. 



Congenital malformations, or native peculiarities in the 

 human subject (and equally, indeed, in the lower animals)/ 

 manifest the strong tendency to variability which exists in 

 nature, and the infinity of means which she makes use of in 

 order to accomplish the same ends. Slight deviations from 

 the normal type are distinguished as varieties, while those of 

 a more striking character are known as lusus natures, and 

 those in which the deviation is so marked as to seem out of 

 the course of nature altogether are regarded as monstrosities. 

 These three degrees of deviation have been classified by 

 Buffon as excesses, deficiencies, and misplacements ; and 

 to these Blumenbach has added a fourth, unnatural forma- 

 tions. No hard and fast line of demarcation, can, however, 

 be laid down, as the four divisions are frequently combined 

 in one example, and each may in some degree co-exist with 

 each the grades and kinds of abnormal variations being 

 simply infinite. Different varieties may not only occur in 

 the same individual, but in different members of the same 

 family ; and both excess and deficiency may co-exist in one 

 subject, as in having too many fingers on .one hand, and too 

 few on the other. One part may be over-developed, whilst 

 another in the same subject is deficient, as in cases where 

 supernumerary fingers are associated with hare-lip or spina 

 bifida ; and, in the same family, one member may have 

 supernumerary fingers and toes, and another have a deficiency 

 of one or both. Nothing, however, can be more certain 

 than that these developmental freaks, whether of the nature 

 of redundancy or deficiency, are transmissible, and frequently 

 perpetuated through several generations, and therefore, as 

 Ribot says, of great interest as shewing that " the individual 



