142 HISTIOID TUMOURS. 



4. HisTioiD Tumours. 



§ 116. On the capacity of the intermediate apparatus of 

 nutrition for generating embryonic tissue at nearly any point in 

 the body, are also based those higher products of tissue-genesis 

 which we term " growths " in the strictest sense of the word, or 

 more correctly histioid tumours. These are characterised by tho 

 internal continuity of their constituent elements. The majority 

 are made up of only a single tissue ; should they be composed 

 however, of more tissues than one, the component tissues are 

 never isolated, never marked off, as epithelium is marked off from 

 connective tissue, but are in organic continuity with one another. 

 The explanation of this internal continuity is to be sought in the 

 original unity (Gleichartigkeit) of the material of which the 

 tumour is built up, this material being in every case embryonic 

 tissue. From this, by a subsequent process of differentiation, 

 are developed tissues of a higher type, more particularly the 

 connective substances — connective tissue proper, with those of 

 its varieties which occur in inflammatory products (Fibroma 

 and Sarcoma), cartilage (Chondroma), bone tissue (Osteoma), 

 adipose tissue (Lipoma), mucous tissue (Myxoma) ; the higher 

 anomalous tissue??, such as the muscular (Myoma) and the 

 nervous (true Neuroma) are more rarely produced. Their mode 

 of origin however is precisely the same as in foetal development ; 

 i.e. a certain number of embryonic cells are converted into the 

 specific elements of cartilage, bone, fat, or muscular tissue, 

 while the remainder go to form connective tissue ; moreover, an 

 adequate vascularisation partitions out the resulting structures 

 into territories of nutrition, thus incorporating them with the 

 organism as a whole. This ensures the interdependence of the 

 tissues among themselves, as well as their connexion with the 

 organism; the morbid product taking its place as an organ, 

 though a malformed and unnecessary one. Growths of colossal 

 size are often produced without in any way affecting the integrity 

 of the body ; such growths only requiring removal hj the knife 

 to reestablish the status quo ante. 



§ 117. This last statement requires some qualification. Un- 

 fortunately there exist, even among histioid tumours, a certain 

 number to which we are compelled to ascribe a "malignant" 

 character (Malignitas). 



