246 TEXT-BOOK OF BACTERIOLOGY. 



latency of tubercular germs lately received, prove the view repre- 

 sented by Baumgarten to be entirely untenable. If we may state 

 our view of these things in brief, we declare that tuberculosis is an 

 infectious disease, caused by a specific bacillus and transmitted to 

 man mostly through inhalation of dried sputum of the lungs of 

 phthisical persons. 



I 

 IV. LEPRA BACILLUS. 



Leprosy is a disease possessing several points of resemblance 

 to tuberculosis, though in every case distinguished from it by 

 very important and unmistakable indications. In Germany it is as 

 good as extinct, and is only rarely seen now and again in the hos- 

 pitals as an exotic rarity, yet it has persisted in certain districts 

 even in Europe, and is still prevalent in Southern Spain and on the 

 coast of Norway. 



In consequence of the peculiarities of its development and occur- 

 rence it has always attracted the attention of the learned, and has 

 provoked great differences of opinion as to its nature and its causes. 

 In the year 1880 Armauer Haiisen, a physician at Bergen, pro- 

 claimed as the result of many years' investigation that he had 

 succeeded in many cases of leprosy in recognizing the presence of 

 bacteria. These, he said, were to be found chiefly in the nodules 

 characteristic of the disease, and usually possessed the shape of 

 rod-cells. Hansen's statements were corroborated by Neisser, and 

 the lepra bacilli have since become generally recognized. 



They are slender, moderately-large rod-cells, with sharp ends 

 almost identical with the tubercle bacilli in appearance; perhaps a 

 little shorter. The lepra bacilli, like the tubercle bacilli, have no 

 voluntary movement. Whether the oval or round spots which in 

 stained bacilli appear as light uncolored portions in the interior of 

 the cells are to be regarded as spores or not cannot as 3 T et be 

 decided, and there are no facts known which would point to the 

 necessary existence of enduring forms. 



As to the staining of the bacilli, we already know that they are 

 the only species of bacteria as yet known to which the special 

 procedure employed for tubercle bacilli is also applicable. Yet the 

 staining of the lepra bacilli is performed with much more ease and 

 rapidity, and Ziehl's solution penetrates without difficulty into the 

 bacterial protoplasm. Gram's method is also recommended, as it 

 brings out the cells beautifully and is specially adapted for accurate 

 investigations. 



The lepra bacilli and the tubercle bacilli are at once distinguish- 



