THE BONES AND JOINTS. 



731 



but, as above described, in a series of irregular spicula or masses. More- 

 over, as will be seen further on, the conditions under which it is formed 

 being liable to change, and itself serving no definite purpose in the econ- 

 omy, as does normal bone, pathological new bone is often an evanescent 

 structure. The details of its disappearance will be considered below. 



Syphilitic Periostitis. Syphilitic infection may excite simple, purulent, 

 fibrous, or ossifying periostitis. In addition to these, gummy tumors 

 may be developed in the periosteum. The bone tissue is usually more or 

 less involved. The gumniata may be absorbed or undergo cheesy degen- 

 eration, or be converted into fibrous tissue, or they may suppurate. 



Tuberculous Periostitis. In badly nourished persons, particularly in 

 children suffering from scrofula, chronic purulent periostitis is frequently 



FIG. 484. TUBERCULOSIS OF THE JOINT. 

 Shows caries with extensive destruction of the bone. 



associated with the formation of miliary tubercles. Abscesses are apt to 

 form in and about the periosteum, and when these are evacuated granu- 

 lation tissue may develop, which contains miliary tubercles. The bone 

 is apt to be involved to a greater or less extent in simple inflammatory 

 changes or caries (Fig. 484). 



OSTEITIS. 



Inflammation in bone tissue is dependent upon the same general con- 

 ditions and presents essentially the same series of phenomena as inflam- 

 mation in other kinds of connective tissue. But it is variously modified 

 in detail by the peculiar dense and unyielding character of the basement 

 substance, and by certain peculiarities of the blood supply and the 

 nutritive conditions under which the cells are placed. In simple exuda- 

 tive inflammation the same series of phenomena occur in connection with 

 the blood-vessels as in other tissues, resulting in the production of serum, 

 fibrin, and pus ; but the extent to which these changes occur is lim- 

 ited and constantly associated with striking alterations in the basement 



