CAVERNOUS TUMOURS. 165 



dilatation of the blood-channels ; i.e. a shortening of the trabe- 

 cul^e and an enlai'gement of the nodal points of that network 

 which is constituted by the blood. 



§ 131. Fig. 54 may serve to elucidate the above remarks ; it 

 represents the development of a cavernous tumour from adipose 

 tissue. We see three clusters of fat-cells which correspond to as 

 many stages of the cavernous metamorphosis. The least altered 

 cluster exhibits the well-known capillary network, which is made 

 apparent, in the present instance, not by injection, but by the 

 walls of the vessels being coated with numberless round connec- 

 tive-tissue corpuscles. It is highly probable that these cells are 

 colourless corpuscles which have migrated from the blood ; this 

 part of the process might then be regarded as a very insidious 

 inflammatory change limited to the immediate neighbourhood of 

 the vessels. In the adjoining cluster the process is so far 

 advanced that only scattered fat-cells are still intact, all else 

 having been transformed into embryonic tissue. This is begin- 

 ning to undergo conversion into fibrous connective tissue along 

 the course of the vessels, which gape widely, especially at their 

 nodal points. 



The third cluster shows the erectile tissue in its maturity ; 

 (cf. fig. 52) ; what was the parenchyma is now a system of 

 trabecula?, towards which the blood-containing spaces stand in 

 the same quantitative ratio as that in which the parenchyma 

 stood towards the vascular network in the least-altered cluster. 



Thus we see that the cavernous growth originates in a fibroid 

 degeneration of the capillary portion of the blood-path ; it is a 

 mistake therefore to derive it from an ectasy of the veins or 

 arteries. This must not be taken to mean that the larger 

 afferent and efferent vessels of the area under2:oino: deo^eneratlon 

 remain unaltered. The arteries of the cavernous tumour more 

 especially show an enormous thickening of their walls, a tortuous 

 course, and a capacity for dilatation such as no healthy vessels, 

 save the helicine arteries, ever exhibit. The annexed figure 

 likewise informs us concerning their relation to the blood-spaces 

 of the erectile tissue. They communicate with these spaces by 

 as many apertures as there formerly were communications 

 between the arterioles and the capillary network. The amount 

 of blood In the erectile structure depends immediately on the 

 degree in which the arteries are contracted. In fig. 54, besides 



