690 INFECTIOUS DISEASES. 



The mammary lymphatic glands are affected in the same way as other 

 lymphatic glands. 



In the joints tubercles appear either on the synovial membrane or 

 in the thickness of the bony epiphyses, very often at both points simul- 

 taneously. The synovial membrane is covered with vegetations and 

 villous growths, the ends of the bones are attacked by a destructive 

 ostitis, tubercles or tuberculous centres form in the thickness of the 

 spongy tissue, the articular cartilages are destroyed, the ends of the 

 bones become deformed, and in the last stages fungoid arthritis in 

 various forms may be produced. 



In bones the tubercles originate in the depths of the spongy tissue. 

 They produce destructive hypertrophic ostitis, in which the bony tissue 

 is replaced by tuberculous centres or masses divided by fibrous parti- 

 tions. On section, these lesions exhibit the same yellowish caseated 

 or calcified appearance as the lesions of other affected organs. The 

 compact layer may sometimes be perforated at several points before 

 being destroyed. 



In tuberculosis of the brain the primary lesions develop at tlie 

 expense of the serous layers of the arachnoid and on the pia-mater, 

 towards the base of the brain and the fissure of Sylvius, or at the 

 expense of the small vessels which penetrate the depths of the nerve 

 substance itself. Some tubercles remain isolated, become confluent or 

 are collected in masses of different sizes, and provoke symptoms which 

 vary with the locality attacked. 



Symptoms. Tuberculosis is the most protean of all diseases, and 

 at first sight it often seems impossible to assign to one group, clinical 

 conditions presenting such essentially different appearances. All the 

 tissues may be attacked, from the bones to the most delicate of the 

 viscera, a fact which explains why all aspects of tuberculosis cannot 

 be described. Certain forms, however, occur very frequently, and 

 may be regarded as classic ; these will be considered in the order of 

 their frequency. 



TUBERCULOSIS OF THE RESPIRATORY APPARATUS. 



Without doubt this form of tuberculosis is by far the most fre- 

 quent. It assumes the form either of bronchitis, laryngo-bronchitis, 

 or pulmonary tuberculosis. 



Tuberculous Bronchitis. — The symptoms of tuberculous bronchitis 

 do not essentially differ from those of ordinary bronchitis, though the 

 disease develops more insidiously and slowly, and is seldom accom- 

 panied by fever. At first the cough is dry and suppressed ; later it 

 becomes paroxysmal, and at a still more advanced period liquid and 



