674 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
tubercle bacilli in media containing vegetable, viz.: — (1) 4 per cent, 
glycerinised potato-broth ; (2) 4 per cent, glycerinised potato-agar ; 
(3) 4 per cent, glycerinised potato-meat-pepton-bouillon ; (4) 4 per cent, 
glycerinised potato-meat-pepton-agar. On the first two the tubercle 
bacillus was found to thrive just as well as on the ordinary glycerin-meat- 
pepton-bouillon, while on the last two the energy of growth was almost 
twice as great. Cultivations of the tubercle bacillus were also made on 
media of similar composition but with acid reaction. Of these the agar 
cultures showed a brownish-yellow pigmentation ; the virulence was 
only half as great as that of ordinary cultures ; microscojncal examina- 
tion showed that the cultures consisted of long filaments (in the bouillon 
cultures they were especially long). No lateral branching was noticed. 
By transferring these cultures to alkaline media the ordinary bacillar 
form reappeared. The author regards the filaments as heteromorphic 
forms of the tubercle bacillus produced by growth on acid media. 
Morphology of Tubercle and Glanders Bacilli.* — Herr Seminer 
found in old tubercle cultivations on potato which had been grown 
in a thermostat at temperatures varying from 25°-35°, dichotomously 
branched, long, matted filaments, the thickness of which was much 
greater than that of ordinary tubercle bacilli, being about the same as 
that of anthrax in the blood. In the filaments were bodies, in part 
staining darker, in part remaining unstained. The author considers 
the filament form as the perfectly developed stage of the tubercle 
bacillus, which grows as a saprophyte at low temperatures, while in the 
human and animal body the short small bacilli are an intermediate 
stage adapted to altered conditions. The glanders bacillus is also 
pleomorphic and variable ; for under certain circumstances it grows into 
long filaments with vesicular and club-shaped expansions, and also with 
unstained refracting vacuole-like corpuscles. These corpuscles ap- 
parently consist of mucoid or colloid substance, and have some con- 
nection with the formation of resting-forms. If animals be inoculated 
with cultures consisting of the long filaments, they die of glanders, and 
only the ordinary bacillus of glanders is found in their organs. The 
author is of opinion that all pathogenic micro-organisms are originally 
saprophytes, and only appear in the human and animal organisms in 
intermediate and transition stages. Hence they must all be potential 
and not essential parasites. 
Serum Therapeutics of the Plague.f — MM. Yersin, Calmette, and 
Borrell have made experiments for the purpose of demonstrating the 
possibility of immunising animals against the plague, and of curing 
those already attacked by the disease. Cultures on gelose heated to 58° 
for an hour were injected into the veins, the peritoneal sac, and beneath 
the skin of rabbits. The animals were found to have become immune 
to inoculations of the living virulent microbe, 2 )rov ided that they 
had quite recovered from their previous illness. Positive results were 
obtained from the serum of the immunised animals, three cubic centi- 
metres of serum being sufficient to protect a fresh rabbit from virulent 
* Zeitschr. f. Tiermed. u. Vergleich. Pathol., xxi. pp. 212-6. See Centralbl. fi 
Bakteriol. u. Parasitenk., l te Abt., xviii. (1895) pp. 68-9. 
f Ann. lust. Pasteur, ix. (1895) pp. 589-92. 
