HOMOLOGOUS AND HETEROLOGOUS NEW FORMATION. 487 



tion is analogous to the old one, as some product or 

 other deviating more or less from the original type of 

 the part. This is the point of view to which I have 

 already (p. 93) directed your attention when treating of 

 the classification of pathological new-formations. By it 

 is a reason, sensible and in correspondence with the facts, 

 afforded for the separation of all new-formations into 

 homologous and heterologous ones. 



Heterologous we may call not only malignant, degene- 

 rative neoplasms, but we must also thus designate every 

 tissue which deviates from the recognized type of the 

 part, whilst we should call all that homologous, which, 

 although new-formed, still reproduces the type of its 

 parent soil. We find, for example, that- the so ex- 

 tremely common form of uterine tumour, which has 

 been designated fibrous or fibroid, has in every respect 

 the same structure that the walls of the " hypertro- 

 phied " uterus have, inasmuch as it consists not only of 

 fibrous connective tissue and vessels, but also of muscu- 

 lar fibre-cells. The tumour may, as it is well-known, 

 become so large, as not only to embarrass the uterus 

 in all its functions in an extreme degree, but also to 

 exercise through pressure the most injurious influence 

 upon the neighbouring parts. In spite of this, it must 

 always be considered an homologous structure. On the 

 other hand we cannot help employing the term hetero- 

 logous formation, as soon as, by means of a process 

 which at first seems to represent a simple multiplication 

 of the parts, a result is obtained which is essentially 

 different from the original condition of the spot. A 

 catarrh for example in its simple form may be attended 

 by a multiplication of the cellular elements on the sur- 

 face of the mucous membrane, without the new cells' 

 being essentially different from the pre-existing ones. 

 Thus I brought along with me for you last time a vagina 



