A CONTRIBUTION TO THE MORPHOLOGY OF BACTERIA. 38 
blance of the acute disease they are capable of producing in 
rodents. But it is noticeable amongst them that while some 
preserve the same definite shape when grown in one species of 
animals or one kind of medium, this becomes changed under 
other conditions. Take, for instance, the bacillus of grouse 
disease: in the grouse itself, taken from the liver or cultivated 
in gelatine, it appears in a short oval form; but in the guinea- 
pig or in the mouse the cells are more commonly of a cylin- 
drical form, and so also in the gelatine culture from the blood 
of these animals. 
Amongst the best known examples of permanency of shape is 
that of the Bacillus anthracis; so much so that its cylin- 
drical elements, single and in short and long chains in the 
blood of an animal dead of anthrax, have become as much the 
classical illustrations of typical bacilli as those of the Bacillus 
subtilis. 
A. In the year 1883 (see this Journal, vol. xxiii) I have 
described a peculiar change of the anthrax bacilli in culture, 
in the course of which the typical cylindrical cells constituting 
the well-known threads become transformed into oval and 
spherical corpuscles, some containing vacuoles. This change 
was named a torula form, because some of the threads resemble 
in a remarkable manner the chains of cylindrical, oval, and 
spherical cells which are observed on Saccharomyces my- 
coderma of thrush. The direct connection between the 
typical cylindrical cells and the spherical and oval corpuscles 
(three and more times the diameter), and the division of these 
into similar corpuscles, was traced in many filaments through 
all intermediate stages (fig. 1). 
At that time I insisted on these changes not being due to 
involution and degeneration, but belonging to an active phase 
of growth in the artificial media. In the first place it was then 
shown that this morphological change is observed already in an 
early stage of growth, when of degeneration there can be no 
question ; besides, in later phases, after two, three, and more 
days’ growth, the progress of the growth and the resulting 
filaments are again of the characteristic appearances. I have 
