274 TUBERCULOSIS 



The bacilli in the tissues occur scattered irregularly or in 

 little masses. They are usually single, or two are attached end 

 to end and often form in such a case an obtuse angle. True 

 chains are not formed, but occasionally short filaments are met 

 with. In cultures the bacilli form masses in which the rods are 

 closely applied to one another and arranged in a more or less 

 parallel manner. Tubercle bacilli are quite devoid of motility. 



/--~7 r^\ 



* 









FIG. 79. Tubercle bacilli in phthisical sputum ; they are longer than 



is often the case. See also Plate II., Fig. 7. 



Film preparation, stained with carbol-fuchsin and methylene-blue. 

 x 1000. 



Aberrant Forms. Though such are the characters of the 

 organism as usually met with, other appearances are sometimes 

 found. In old cultures, for example, very much larger elements 

 may occur. These may be in the form of long filaments, some- 

 times swollen or clubbed at their extremities, may be irregularly 

 beaded, and may even show the appearance of branching. Such 

 forms have been studied by Metchnikoff, Maffucci, Klein, and 

 others. Their significance has been variously interpreted, for 

 while some look upon them as degenerated or involution forms, 

 others regard them as indicating a special phase in the life- 



