166 POULTRY DISEASES 



connective tissue of the periosteum, as well as that of the tissue 

 from which the osteoma arises; and also from that of the 

 perichondrium and endosteum. If an exostosis develops^ in 

 such a manner that cartilage is first formed from the prolifer- 

 ating periosteum or bone marrow, and from that cartilage, 

 bone is later developed, it is called a cartilaginous exostosis; 

 when the exostosis is formed directly from the proliferating 

 periosteum without an intermediate stage of cartilage, it is 

 known as a connective tissue exostosis. 



If the connective tissue in a bony tumor is abundant, and 

 in fact a predominating substance, it is called an osteofil)roma. 

 This form of tumor appears quite commonly among bony 

 tumors. 



An abundant production of bone in a chondroma leads to 

 the formation of an osteochondroma. These latter are usually 

 found in the long bones. 



A condition in which the muscles become bony in nature 

 is called myositis ossificans. The tendons of birds and es- 

 pecially those of the leg often become ossified, especially in 

 old birds. This is also the case in some of the vertebral liga- 

 ments. 



One case of generalized osteoma has been studied in a fowl. 



HORNY GROWTHS ON THE CUTICULAR SURFACE OF 



FOWLS 



Horny growths are reported as occurring on the cuticalar 

 surfaces of fowls, by Gadow. Horny growths have been ob- 

 served on the cuticular surfaces and on different parts of the 

 body of cattle and other animals. 



A case which Ave have observed is of importance on account 



of its immense size as compared to the size of bird upon which 



it was found. 



Dr. Leonard of Asheville sent to this laboratory a specimen with 

 the case history that it was excised from the thigh region of a 

 two-year-old hen. No further history could be obtained. The spec- 

 imen measured 14 centimeters long and 7.5 centimeters in diameter 

 at the base. The outer structure is horn-like, resembling the horny 

 structure of the spur or claw. There will be noted that here and 

 there a feather has developed. The inner core consists of con- 

 nective tissue and some adipose tissue and is soft in consistency. 



PAPILLOMA— WARTS 



True papillomata have been observed in the fowl. They 

 occur on the cuticular surface and consist of a connective 

 tissue core covered by stratified epithelia. 



