410 TUMOURS. 



degenerate elements of the epithelial contents of the tubes and 

 acini. But among all these lie the proper cells of the cancerous 

 growth, and these usually increase while the original structures 

 of the gland decrease. So, too, in medullary cancerous disease of 

 the uterus, the uterus itself, or part of it, is in the tumour and 

 gradually disappears, while the medullary matter diffused or in- 

 filtrated in it is growing. 



" The malignant growths may, I say, thus appear as infiltra- 

 tions ; but they are not always so. Thus, though the hard cancer 

 of the breast is, commonly or always, an infiltration of cancerous 

 substance in and among the proper structures of the gland, yet 

 the hard cancer of the bones is often a distinct tumour, such as 

 has no mixture of bone in it, and may be enucleated from the 

 cavity or shell of bone in which it lies. So, too, while the 

 medullary cancer of the uterus plainly consists in an infiltration 

 or insertion of new material in the substance of the organ, that 

 of the breast is usually a separate tumour, and altogether dis- 

 continuous from the surrounding parts. 



" Many other instances of similar contrast might be cited ; 

 still the fact that their elementary structures may be thus infil- 

 trated in the tissues they affect is a characteristic feature of 

 malignant tumours. I think it is rarely imitated in cases of in- 

 nocent tumours. 



" od. It is also generally characteristic of malignant tumours 

 that they have a peculiar tendency to ulcerate, their ulceration 

 being preceded by softening. One can, indeed, in this particu- 

 lar, only observe a graduated difference between the innocent and 

 malignant diseases ; for certain innocent tumours, if they grow 

 very rapidly, are apt very rapidly to decay ; and they may sup- 

 purate and discharge their ichor and debris with foul and 

 dangerous ulceration. Thus the quickly growing cartilaginous 

 tumours may imitate in these respects the malignant growths ; 

 so may large fibrous tumours when they soften and decay. Or 

 again, when an innocent tumour grows more rapidly than the 

 parts over it can yield, they may waste and ulcerate, and allow 

 it to protrude ; and it may now itself ulcerate and look very 

 like malignant disease. This may be seen in the protruding 

 fibrous tumours that ulcerate and bleed ; or, in a more striking 

 manner, in the protruding vascular growths that have sprung 

 up in the cystic tumours of the breast. Or, once more, the 



