TUMORS. 



513 



quainted with the fact that the blood-vessels are really new 

 formations. We can distinguish three varieties of angioma, 

 according to the nature and distribution of the blood-vessels 

 simple, lobular, and cavernous angioma. 



(a) Simple angioma is, to a great extent, composed of newly 

 formed capillary blood-vessels, between which, in more or less 

 uniform distribution, is a varying amount of fibrous or homo- 

 geneous connective tissue. The 

 coat of the blood-vessels is com- 

 posed of very large nucleated, 

 sometimes stratified, endothe- 

 lia j numerous tracts are solid, 

 and composed entirely of en- 

 dothelia (endothelioma). Both 

 in the endothelia and the con- 

 nective-tissue frame there are 

 indications of a new forma- 

 tion of red blood-corpuscles, 

 through- the intermediate 

 stage of haematoblasts. (See 



Fig. 209.) 



(~b) Lobular angioma is 

 composed of coils of large 

 capillary blood-vessels, held 

 together by delicate fibrous 



tissue, while between the coils FIG. 209. SIMPLE ANGIOMA, FROM 

 this tissue is somewhat denser. 

 The lobate structure is some- 



, -I -i , ,-1 -i -i L, longitudinal section of a capillary; S, 



Times marKea IO tne naxea soli(1 cor(1 of eudothelia; F, frame of a nearly 



eye. In Sections, the blood- homogeneous connective tissue. Magnified 



, . . , 7 ., T T 600 diameters. 



vessels are cut in longitudinal, 



oblique, and transverse directions, and are found either empty 

 or filled with blood. The capillaries are connected with large 

 arteries or large veins, and the blood in the angioma may be 

 clinically recognized as being of either venous or arterial char- 

 acter. (See Fig. 210.) 



(c) Cavernous angioma is constructed on the plan of cavern- 

 ous tissue i. e., composed of venous sinuses, which lie close 

 to each other, separated only by walls of fibrous tissue, in 

 which are capillary blood-vessels, and sometimes bundles of 

 smooth muscle-fibers. The cavernous sinuses -are filled with 

 blood-corpuscles, and the blood has in its clinical aspect a venous 



THE SKIN" OF THE FOREHEAD OF A 



CHILD. 





33 



