TUMOURS OF THE HEART. 375 



symptoms at a comparatively early period in the hard- 

 worked horse. 



With regard to external tumours, their weight is some- 

 times very great, and, when connected with the apex, may 

 attain a size far exceeding that of the heart itself, without 

 inducing very serious symptoms. This is not the case when 

 the deposits invade the base of the heart, where they obstruct 

 the vessels and arrest the circulation. If the veins are chiefly 

 implicated, dropsical effusions, with symptoms of debility, 

 palpitating heart, and coldness of the extremities, &c., are 

 observed. If the arteries become constricted, tne imperfect 

 flow of blood soon leads to great prostration and hectic, the 

 animal lingering on to die in a state of great emaciation. 



The tumours examined, and which are connected with the 

 exterior of the heart, originate in the substance of, or immedi- 

 ately beneath the pericardium, which yields, and is continu- 

 ous in all cases I have examined with the envelope of the 

 growth. The tumours are usually unattached to the parietal 

 layer of the pericardium, and lie free in the pericardial sac. 



The tumours are often multiple, and this is chiefly the 

 case in cancer and melanosis. 



1. With regard to the parasitic growths, I have examined 

 in Bologna a polypus containing as its nucleus a cyst, within 

 which were admirable specimens of echinococcus veteri- 

 norum. Another remarkable specimen, preserved in- the 

 museum in that city, consists in a large mass of cysts hang- 

 ing from the apex of the heart of an ox. These are cysts of 

 the same parasite. Gysticercus tenuicollis has been met with 

 in the pericardial cavity; cysticercus cellulosce, in the sub- 

 stance of the heart of the pig; and dochmius trigonocephalus 

 in the cavities of the heart of a dog. 



2. I have seen several instances of melanosis implicating 

 the heart, but only recognised after death. 



