THE TUBEBCLE BACILLUS 269 



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, sometimes swollen or clubbed at their extremities, 

 may be irregularly beaded, and may even show the appearance of branch- 

 ing. 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-history of the organism, 



< m k - 



Fig. 74. — 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. 



allying it with the higher bacteria. Recent observations, however, go to 

 establish the latter view, and this is now generally accepted by authorities. 

 It has also been found that under certain circumstances tubercle bacilli in 

 the tissues produce a radiating structure closely similar to that of the 

 actinomyces. Club-like structures maybe present at the periphery. This 

 was found by Babes and also by Lubarsch to be the case when the bacilli 

 were injected under the dura mater and directly into certain solid organs, 

 such as the kidneys in the rabbit. Similar results obtained with other 

 acid-fast bacilli will be mentioned below, and these organisms would 

 appear to form a group closely allied to the streptothriceae, the bacillary 

 parasitic form being one stage of the life-history of the organism. This 

 group is often spoken of as the mycobacteria. 



