96 LECTURE III. 



springs, and at the very point where real cartilage ex- 

 ^ ists, for example, at the articular ends of the bone, no 

 cartilaginous tumours, in the ordinary sense of the word, 

 arise. It is not, therefore, with an hypertrophy of pre- 

 '01, existing cartilage that we have here to deal, but with a 

 : genuine new formation, which begins with a change in 

 the local histological type. According to this manner 

 f- of viewing the subject which is essentially different from 

 that previously current, no attention is therefore paid, 

 in considering the question of the heterologous nature of 

 a new formation, to the composition of the structure as 

 such, but only to the relations which subsist between it 

 and the parent soil from which it springs. Heterology, 

 in this sense, designates the difference of development 

 \ in the new, as contrasted with the old, tissue, or, as we 

 ( are wont to say, a degeneration, a deviation from the 

 typical conformation. 



This is, as you will see, also really the most important 

 point upon which we can ground our prognosis. We 

 find tumours, which present the most striking resem- 

 blance to the most familiar physiological tissues. An 

 epidermic [epithelial] tumour (Epidermis-Geschwulst) 

 may, as I have already pointed out, in its elementary 

 structure entirely correspond to ordinary epidermis, but 

 in spite of this it as not always a benignant tumour of 

 merely local import, which may be traced to a merely 

 hyperplastic increase in pre-existing tissues, for it some- 

 times arises in the midst of parts which are far from 

 containing epidermis or epithelium, as, for example, in 

 the interior of lymphatic glands, or in that of thick 

 layers of connective tissue, which are at a distance from 

 any surface, and even in bone. In these cases the for- 

 mation of epidermis is certainly quite as heterologous as 

 it is possible to conceive anything to be. But practical 

 experience has shown us that it was altogether incorrect 



