TRANSACTIONS OF SECTION K. 1015. 
minute, after ten minutes they are more or less globular, then pass through changes 
similar to those described above, and after some days resume their spindle shape—an 
indication of rest. 
2.. On the so-called Tubercle Bacillus. By A. Coreen Jones, F.L.S. 
(Communicated by A. VAUGHAN JENNINGS, F.L.8., F.G.S., &c.] 
Since the demonstration by Robert Koch in 1882 of a specific micro-organism 
constantly associated with and capable of producing tuberculous disease, the 
Bacillus tuberculosis has been the object of a great amount of investigation, which 
has resulted in a vast accumulation of literature. The minute rod-like organism 
which bears the name is better known to pathologists than any other pathogenic 
fungus, and may be easily diagnosed by the characteristic and unique appearance 
of its pure cultures on solid media, by the difficulty of staining it with the ordi- 
nary aniline dyes, and by the resistance it offers when stained to the decolorising 
action even of mineral acids. 
Its claim to be regarded as a true bacillus has only very recently been ques- 
tioned, but there are several considerations which tend to modify our views with 
respect to its biological status ; and the following observations, made during the 
last few years, and continued up to the present time, are, from this point of view, 
not without interest :— 
1, While the well-known simple rod-like form is by far the commonest, and, 
n fact, the only form to be found in the vast majority oi cases, whether in the 
tissues, in sputum, or in cavity contents, there may be observed, not infrequently, 
elongated examples which develop lateral outgrowths, twigs, or incipient branching. 
2. In rarer cases this process results in the formation of definite threads or 
hyphee, which exhibit true branching, and often contain one or more spores, 
forming oval, highly refracting, deeply stained swellings on the course of the 
filaments. It is to be particularly noted, first, that these spores have far more 
resemblance to the chlamydospores of the true filamentous fungi than to the 
typical endospores of bacteria ; and, secondly, that they must on no account be 
confounded with the unstained intervals on the course of the rods or filaments of 
the tubercle organism. These were formerly described by Koch as spores, but are 
really vacuoles in the cell contents, or, in some cases, spaces caused by the plasmo- 
lytic shrinkage of the protoplasm. Occasionally, in cavity contents, densely 
matted mycelial growths have been observed. 
3. When old cultures are examined by means of sections it is found that the 
growth does not consist of separated rod-like forms, isolated from one another and 
lying at all angles, but of strands of parallel filaments, frequently showing 
dichotomous branching 
4. These facts indicate that the so-called ‘tubercle bacillus’ is! really a stage 
in the life-history of some higher form of fungus with a definite mycelial growth. 
From a systematic point of view, it cannut be regarded as coming within any 
definition of the genus Bacillus, and it is suggested that a more appropriate name 
would be Tuberculomyces. 
Pathologists, who for the most part believe strongly in the constancy of form 
of the species of bacteria, may not be inclined at first to accept these conclusions. 
Bearing in mind the controversies of the past on the specific distinctness of micro- 
organisms and the many erroneous observations which have led to false statements 
as to polymorphism, such scepticism is both natural and desirable; but in the 
present case the tracing of all stages between the short rods and the branched 
hyphal filaments, their identical behaviour towards reagents, and the occurrence of 
all these forms in pure cultures, place their genetic relationship beyond a doubt. 
Brefeld has proved that a number of the higher thallus-forming fungi may, 
under certain conditions, multiply for innumerable generations as mere unicellular 
rods or spheres (‘oidia,’ &c.), and yet retain the power of again forming, when 
placed under suitable conditions, the mycelium from which they arose. It is 
