352 Tumors. 



Isolations of bits of tissue from either of these sources may occur 

 in embryonic Hfe from developmental faults, as in the formation 

 of the branchial arches or the primitive vertebrae and embryonal 

 elements of the ribs. The fact that chondromata may be congen- 

 ital is an argument for this view. In the postfcetal period car- 

 tilaginous isolations may take place from disturbance in growth 

 in the skeleton (rachitis) ; and traumatic lesions, as fractures of 

 ribs, may give origin to separation of bits of perichondrium, and 









Fig. 94. 

 • Section of a chondroma from a hen. 



these in association with profuse callus formation might develop 

 into chondromatous tumors. 



Chondromata are most common in the bony framework of the 

 chest as the result of fractures of the ribs, projecting into the 

 chest cavity or beneath the skin as large tumor masses; they are 

 also frequently met in the neighborhood of the jaw and thyroid 

 gland, originating from remnants of the branchial cartilages, in 

 goats, horses, dogs and cattle. /\s mixed growths (chondro- 

 adenoma) they have been seen a number of times in the lungs, 

 mammary gland and in the testicles in animals. As exceptionally 

 rare instances may be mentioned enchondromata of the vitreous 



