CONTAGIOUSNESS OF TUBERCULOSIS. 
823 
(3. — CONTAGIOUSNESS OF TUBERCULOSIS. 
By Dr. F. H. VIVIAN VOSS, F.R.C.S . , En<j„ Ac. 
The first remark I can remember hearing in relation, to medicine 
and the medical profession was that by an old man to the effect that 
consumption was a standing reproach to the medical profession, and 
would be so as long as it continued such an unchecked scourge to 
mankind. Since then (nearly twenty-five years ago) steady advance 
has been made. We know much of the cause and origin of tuber- 
culosis, though by no means all. The great discovery that the 
tubercles or foci of the disease contained a virus or poison capable of 
producing the malady when inoculated into the lower animals was 
made by Klencke and Vi lie min.* 
Later Burdon Sanderson, Klebs, and others repeated and con- 
firmed their experiments ; but it is now, I think, universally admitted 
that the causa causans is the tubercle bacillus discovered by Koch in 
1882, and he was so exact in his original papers that, Von Ziemssen 
says, it was found that all the criticism and investigation which 
followed his solution of the problem not only made no essential 
change but no important addition to his statements. Every link in 
the chain of evidence was firm. 
The human Bacillus tuberculosis is a rod-shaped microbe, in 
length rather less than the diameter of a human red blood corpuscle. 
When stained and very highly magnified the bacillus presents a dotted 
appearance, showing that the protoplasm forming its body is inter- 
rupted. It is not proved so far that either the stained granules or 
the bright spaces are spores, as has been stated by various observers. 
That the tubercle bacilli contain spores is proved by certain experi- 
ments of drying and heating; but what the character of these spores 
is, and how they appear in the bacilli, has not been satisfactorily 
shown. In bovine tubercular matter the bacilli are, as a rule, shorter 
and thinner than those found in human tubercular matter, and the 
division of the protoplasm is not so general and uniform. But these 
minute differences need mean nothing more than differences due to 
the different soils on which the bacilli were raised. Such morpho- 
logical differences arc well known to occur in other instances if the 
mmrobe be cultivated in different soils. When the tubercle bacilli 
obtained from any source, bovine or human tuberculosis, or from 
artificially infected animals, are passed through the rabbit or the 
guinea-pig, in these animals the new crop of bacilli all appear to be 
morphologically the same. I quote the foregoing from Klein’s recent 
essay on the ‘‘ Pathology of Infectious Diseases,” which is quite the 
opposite view of what he formerly published in his book, Micro- 
organisms and Disease,” wherein he writes : “ I cannot for a moment 
accept the statement that the bacilli are identical in the two diseases, 
human and bovine tuberculosis.” This change of opinion in such ail 
eminent authority is very valuable and well worth noticing. 
Tuberculosis is a term covering many diseases, apparently 
different diseases. It may perhaps best be defined as that disease 
which is casually related to the operation of the tubercle bacillus. It 
* Etude sur la Tuberculose, Paris, 1865. 
