TUMORS. 



359 



the case and the structure and evidences of proliferation presented 



by the tumor itself. 



FIG. 322. 



Angiosarcoma of bone. (Kaufmann.) The lumina of bloodvessels are seen in longitudinal 

 and in cross-section. They are surrounded by a highly cellular tissue, derived from the 

 proliferation of the endothelium forming the perivascular lymphatics. Such tumors are 

 also called " peritheliomata." 



7. Sarcoma. This term includes a variety of tumors differing in 

 the details of their structure and in their clinical significance, but 



FIG. 323. 



Endothelioma of the thyroid. (Limacher.) In this example the endothelial cells of the 

 tumor spring from the endothelium of the capillary bloodvessels. Various stages in the 

 proliferation of that tissue are represented in the section. 



having in common a general resemblance to imperfectly devel- 

 oped or embryonic connective tissue. Such tissues are not infre- 



