318 



TUMOKS. 



to the development of irregular masses of new bone within them, thus 

 forming one of the varieties of osteo-sarcoma. 



^v-^Osteo-Sarcoma. These are spindle or round-celled tumors, usually, 

 but not always, connected with bone, in which irregular masses of bone 





. -, 

 U 



FJG. 158. ANGIO-SARCOMA. 

 Tumor from the arm. Sometimes called perithelial sarcoma. 



tissue are present. The bone is usually of irregular atypical structure, 

 the regular lamellation and typical Haversiau canals being usually ab- 

 sent (Fig. 157). They may form metastases which present similar char- 

 acters. 



x^^Angio-Sarcoma. In many of the sarcomata in various parts of the 

 body the blood - vessels form so prominent and important a feature as to 

 give special character to the growth, not alone by their size and general 



FIG. 159. ANGIO-SARCOMA. 

 One of the blood-vessels with its cellular sheath from the tumor shown in Fig. 158. 



prominence (Fig. 158), but sometimes by the peculiar arrangement which 

 their presence gives to the cells. While in most of the sarcomata the 

 blood-vessels have a very important influence in determining the topog- 

 raphy of the tumor, in most of the denser and in many of the softer 

 varieties this influence is not easily traced. In many forms, however, 

 particularly those which are soft and very cellular, the cells are closely 

 grouped around the vessels, developing in their adventitise and forming 



