422 TUMOURS.^ 



parts. They grow deeply in loose areolar spaces, but their 

 boundaries are more superficial where the surrounding struc- 

 tures are firm. The parts around the lobes are not usually 

 infiltrated, as each lobe is surrounded by a more or less distinct 

 capsule, which seems not only to enclose each individual lobe, 

 but to extend over and involve the whole tumour. This is 

 easily separated from the surrounding structures, and when cut 

 into allows its contents to protrude, or, when very soft, to ooze 

 out. The blood-vessels, which are numerous in the capsule, are 

 tortuous in their course, peculiarly friable in their texture, and 

 usually surrounded by the medullary matter. This friability of 

 the vessels renders it very difficult to apply ligatures, as the pres- 

 sure required to arrest the haemorrhage usually breaks through 

 the easily lacerable vessels. 



When cut into, the lobes are seen to be composed of a peculiar 

 soft substance (the medullary matter), which is easily broken 

 and spread out with the fingers. It resembles reddish-coloured 

 brain matter, and is sometimes softer than brain. I have never 

 seen it white, as described by human pathologists ; but the tint 

 is usually clear, that is to say, there is no purulent or fibrinous 

 opacity. Masses of a peculiar looking substance are seen in it. 

 These are yellowish, rounded bodies, similar to very small cysts, 

 and in mass resembling Indian meal or coarse porridge. This 

 matter is often found between the lobes, as well as within them. 

 In their centres the contents of the lobes are seen to be under- 

 going fatty degeneration. 



When the cancer is pressed or scraped, it yields a turbid 

 material, '^ cancer juice," and leaves a small quantity of fibrous 

 tissue, with numerous blood-vessels. This, as well as the cancer 

 juice, is formed during the growth of the cancer, and therefore 

 differs from the " stroma of scirrhus " by being part of the malig- 

 nant growth, and not of the tissue in which it grows. 



It was supposed at one time that the vascular system of these 

 cancers was either exclusively venous or arterial ; but it is now 

 proved, by the experiments of Lebert and others, that they 

 contain arteries, capillaries, and veins, arranged in net-works of 

 varying closeness ; and it is also probable that the difficulty of 

 injecting veins in some of them is due to their being filled with 

 cancerous matters, which stops the injection, after it has tra- 

 versed the capillaries. The vessels are very abundant, and are 

 not only friable in structure, but defective in muscular tonicity. 



