The Tuherch Bactllm. 
87 
destroy the invading micro-organisms. If, on the other hand, 
there is no immunity, the phagocytes are unable to cope with 
the bacteria. The latter destroy the white blood cells, increase 
and multiply, and ultimately destroy their host. 
These phenomena have been studied by the writer after 
injecting a few drops of a cultivation of the tubercle bacillus 
in broth into the dorsal lymph sacs of frogs, and withdrawing 
some of the lymph by means of a capillary pipette at intervals 
of a few hours and then of weeks. The lymph cells, white blood 
cells, or phagocytes, can be seen to take up one or more tubercle 
bacilli, just as an amoeba takes up foreign particles. In some 
cases the cells are completely filled with the bacilli (see Plate 11.^). 
The question arises whether the cells actually take up 
and destroy living tubercle bacilli, or whether the bacilli are 
first destroyed by the blood or lymph which, in animals having 
an immunity, is unsuitable for the growth of the bacilli, or is 
even capable of destroying them. Whichever may be the right 
explanation, the practical lesson is that the tissues and blood 
must be kept in a state of health by proper hygienic surround- 
ings, and by absolutely rejecting tubercular subjects for breeding 
purposes when dealing with animals, and by discouraging mar- 
riage of tubercular persons when dealing with mankind. 
Description of Cultivations of the Bacillus. 
Having explained the method of cultivating bacteria, it may 
be of interest to more fully describe the appearances of the 
cultivations of the tubercle bacillus. During the past year, the 
writer has confirmed and extended the observations of Nocard and 
Roux, and photographs of cultures of the bacillus are given in 
the accompanying woodcuts (Figs. 1-7). The bacillus was 
isolated from the expectoration of a phthisical patient, and 
successive sub-cultures have been prepared up to the tenth 
generation. In these photographs the part of the test tube is 
represented in which the meat jelly has been allowed to set with 
a sloping surface ; on this sloping surface the bacilli were sown 
by means of a platinum needle, the point of which was charged 
with the bacilli. The platinum inoculating needle consists of two 
1 Descbiption of Plate II. 
Tubercle Bacilli and " Phagocytes " of the Frog. 
(a) White blood cells of the frog ; (6) cells enclosing single bacilli ; (c) cella 
enclosing two or more bacilli ; {d) and (e) cells packed with more or less disintegrated 
bacilli, 
