8 E. KLEIN. 
threads with knobbed ends, some branched, others as yet 
unbranched, 
There can be no question about involution, because, as I 
have pointed out (1. c., and ‘Centralblatt f. Bakteriology,’ 
vol.vii, No. 25), the branched nature of the threads and 
the presence of the small lateral buddings conclusively prove 
the active growth. Later, Mafucci (‘Archiv f. Hygiene und 
Infect.,’ xi, p. 445) described the same forms in the culture of 
the tubercle bacilli of the fowl, and Fischel (‘ Fortschr. d. 
Med.,’ Bnd. x, No. 22, p. 908) also of the human tubercle 
cultures ; and this latter observer arrived at the same conclusion 
as myself, viz. that we are dealing with forms which are com- 
parable to a mycelial fungus. 
From all these facts I think we are justified in concluding 
that the above three species are not so well-marked typical 
bacilli as has always been assumed ; that is to say, well-defined 
species of desmo-bacteria in the sense of F. Cohn. True, under 
many conditions they show morphological characters of the 
same kind as the typical bacilli; but under other conditions 
they easily revert to or assume forms by which their relation 
to the Saccharomyces or Oidium (anthrax, diphtheria), or a 
still higher mycelial fungus (tubercle) becomes evident. 
