MELANOSIS, OR MELANOTIC SARCOMA. 439 



consisting of ordinary lymphoid tissue, resembling in fact a 

 hypertrophy of gland. In this form there is a well developed 

 reticulum and endothelial plates, and a normal number of 

 lymphoid cells ; whereas, when it becomes malignant, the cells 

 increase to an enormous extent, the reticulum being at first 

 scanty, but later on the reticulum becomes largely developed, 

 with increase of the endothelial plates, and corresponding dimi- 

 nution of the number of lymphoid cells. But, notwithstanding 

 its cellular character, lympho-sarcoma has little or no tendency 

 to undergo any degenerative changes ; there is no softening, 

 caseation, or calcification as in others, more particularly scrofu- 

 lous glandular growths. 



Symptoms and Clinical Characters. — In cattle these tumours 

 originate most frequently in the lymphatic glands of the head 

 and throat, sometimes commencing in the submaxillary, from 

 thence to the parotidean region, often following the lymphatic 

 tracks, and extending along the course of the trachea, involving 

 the thyroid body, and invading the surrounding tissues, from 

 which, however, it remains distinctly separated ; that is to say, 

 it does seem to infiltrate into, but merely displaces, the sur- 

 rounding tissues. 



I have seen these growths in cattle extending along the inter- 

 muscular spaces in an upward as well as downward direction, 

 and involve the face and upper cervical, as weU as the inferior 

 and lateral aspect of the throat, pressing upon the larynx, 

 pharynx, and large veins, preventing free deglutition, respiration, 

 and return of the blood from the head, which, in consequence, 

 has soon presented a swollen oedematous condition, the animal 

 being in consequence a miserable object. 



The effects of these tumours are similar to those induced by 

 scrofula ; both are incurable, but lymphadenoma has no ten- 

 dency to suppurate or ulcerate, whereas scrofulous or tubercular 

 growths undergo degeneration, soften, and, to some extent, sup- 

 purate, such suppuration giving relief, for a time at least, to 

 distressing symptoms. 



I have not seen any external manifestations of lymphade- 

 noma in the dog, but have met with masses in the spleen, 

 mesentery liver, and kidneys. In one instance, the weight 

 of an agglomeration of these tumours, taken from a fox terrier, 

 was as much as seven pounds — the symptoms prior to death 



