414 TUMOUES. 



^tli. Epitlielial cancer of nose and "bones of the face, reported 

 by Kopp. — Udinhurgh Veterinary Reviciu, 1859-60. 



These examples could easily be multiplied, but I will only 

 add that colloid cancer of the duodenum of the horse has been 

 observed by my colleague. Dr. Young. In my own practice the 

 following instances (in addition to those represented in the photo- 

 lithograph facing this chapter) have been observed : — 1st. ]\Iedul- 

 lary cancers in the scrotum (two instances in geldings) ; 2d. 

 Scirrhus of the penis ; '6d. Large medullary cancer in the seat 

 of an old wound on the thoracic walls of an aged half-bred 

 Arab mare ; 4dh. Scirrhus of the mammary glands in dogs and 

 bitches; K>t]i. Melanotic cancers, some of them isolated tumours; 

 others extensive infiltrations, weighing as much as sixteen pounds 

 in one instance, in the tail, pelvic, inguinal, brachial, bronchial, 

 and mesenteric glands, spinal cord, and other organs of grey 

 horses ; and Qth. Colloid cancer of ovaries and kidneys. 



The origin of cancer has been profoundly studied by patho- 

 logists, but there is still much difference of opinion. Some view 

 it as performing the function of a new excretory organ, or a 

 growth arising for the purpose of eliminating from the S3"stem 

 an unhealthy matter which is generated within it. Others 

 believe that it originates from wandering white corpuscles or 

 leucocytes ; these as it were furnishing the starting-points for the 

 cells of cancer, as of many other new" growths ; whilst otlier 

 observers of great eminence maintain that the cells of schirrus 

 originate in the epithelial cells of a gland ; and others again, 

 equally eminent, are of opinion that they are developed from the 

 connective-tissue cells. Dr. Handfield Jones says that "we 

 should recognise in cancer a grave alteration of the normal 

 formative powers — those real but occult influences which deter- 

 mine that here bone, and there muscle, and there nerve, shall be 

 produced." 



Tlie accompanying woodcuts of cancer cells in their various 

 stages exl libit to a remarkable degree their form and metamor- 

 phosis, as observed by Dr Young and myself in our microscopic 

 examinations of cancer tumours : — 



