384 TUMOURS OF THE HEAET. 



endocardium on the surface of the growth was smooth and 

 free from any change in structure. The growth was diffuse 

 and tapered, as may be seen by the drawing, towards the apex 

 of the heart. 



5. Cancerous growths. The heart is usually involved 

 in cancerous disease only when the constitution fails in 

 cancer of other organs. The deposits are, therefore, secon- 

 dary; though instances are not wanting of cardiac tumours, 

 probably malignant and unconnected with cancer in other 

 organs. Cancer of the heart obeys the same laws of develop- 

 ment as cancer elsewhere. It arises in a circumscribed 

 spot and spreads in every direction, usually towards the base, 

 and invading not only the tissues around the heart and 

 vessels, but destroying the walls of the first and coats of the 

 second by progressive infiltration. 



