DISEASES OF THE HEAET, 267 



course of the new vessels in the tertiary mode of vascularlsation 

 (see K'dllihev^ Handbuch d. Grewebeleliro, 3te Auflage, page 

 607). They describe curves of variable radius, wliich rest at 

 eacli end upon the wall of an already pcr\'ious capillary. The 

 lumen of the new capillary is opened up along this curve. The 

 thread of protoplasm forms a thin coating over the whole of 

 its internal surface, and hardens into a homogeneous capillary 

 membrane ; the nuclei of the cells which take part in the process, 

 are shifted, together with the residual protoplasm, to the outer 

 surface of the membrane, where they figure henceforward as 

 *^ capillary nuclei." 



During the vascularlsation of growing organs, only a small 

 proportion of the existing connective-tissue corpuscles is usually 

 employed in the formation of vessels. Matters take a different 

 course in telengiectasis. This is due to an enormous excess in 

 the development of connecting channels between the main capil- 

 lary loops, operated in the manner I have just described. Telen- 

 giectasis therefore is an overgrowth, not a mere dilatation of the 

 vessels. The cluster of fat-cells, the sebaceous gland, the sweat- 

 gland, the cutaneous papilla, are permeated by an enormous 

 number of very fine capillaries (which are for the most part 

 spirally contorted) in place of the usual network of connective- 

 tissue corpuscles. All the above structures may be recognised 

 in the innumerable lobules of which the telengiectatic part con- 

 sists, even should their specific elements have been destroyed by 

 the pressure of those very vessels wliich were destined for their 

 nourishment. 



The dilatation of the capillaries in the growth of cavernous 

 tumours has already been described (§ 129). 



2. Diseases of the Heart. 



§ 233. In the central organ of the circulatory system we 

 find the same three layers of which the walls of all the greater 

 vessels are made up. The endocardium corresponds to the in- 

 tima, the myocardium to the middle coat, the pericardium to the 

 adventitia. In harmony with the functional superiority of the 

 heart however, each of these three layers is more highly 

 developed, and that in a direction peculiar to itself. 



