482 THIRD PART.-—-BACTERIA OR SCHIZOMYCETES, 
R. Hartig has already drawn attention. One reason for this may be that the parts 
of plants have usually an acid reaction. At the same time Wakker! has recently 
described a disease in the hyacinth known in Holland as the yellow sickness, 
the characteristic symptom of which is the presence of yellow slimy masses of Bacteria 
in the vessels. In the resting (autumnal) bulb the masses of Bacteria are confined 
to the vascular bundles ofthe bulb-scales; at flowering time they are found also in the 
leaves, and not in the vessels only but in the parenchyma also, where they fill the 
intercellular spaces, destroy the cells, and ultimately emerge through the ruptured 
epidermis and appear on the outside. The case demands a thorough investigation. 
The Bacteria on the other hand which are parasitic in living animals are, 
according at least to prevailing views, comparatively numerous, and the most 
prominent feature in them is their facultahve parasitism. Of this we have instances 
which have been investigated with some care and may be considered as well 
established, and it will be well to give here a special account of one of the most 
important of the number, namely Bacillus Anthracis. 
The structure and development of this species have been already portrayed in 
Fig. 195. It attacks the Mammalia, especially rodents and ruminants, with the 
exception of some species and individuals; mice, guinea-pigs, rabbits, sheep and 
cattle are unequally liable to be infected by it in the descending order. It will also 
attack human beings. It is communicated with difficulty to dogs, more readily to 
cats. Observers are not agreed as to the degree of liability of birds, frogs and fishes 
to be infected with it, and we cannot further discuss their statements in this place. 
We know from Rayer, Pollender and Davaine that it causes the disease known as 
anthrax in the animals first mentioned. My own experiments on which this account 
is partly based were chiefly made on guinea-pigs, and on material obtained from 
them. 
When the Bacillus has gained admission into the blood of an animal capable of the 
infection, it grows and multiplies in the rod-form described above to such a degree 
that the entire mass of the blood is permeated by these organisms. The animal 
sickens as the Bacillus multiplies and the result is usually fatal. The Bacillus may 
find its way into the blood directly by intentional introduction of rods or spores or 
from accidental wounds; a prick of a needle charged with rods or spores, so slight 
as not to draw blood, is sufficient to give the infection to a sensitive animal. But it 
may also reach the blood from the intestinal canal, into which it is conveyed in the 
natural way only, that is through the mouth with the food. Rods introduced in this 
way have no further effects, if the digestive passages are without a wound; they 
probably perish in the acid contents of the stomach. But if spores are introduced the 
animal takes the infection. The spores pass unharmed through the acid stomach 
and germinate in the alkaline contents of the intestinal canal, and the rods which are 
the product of germination are found in the mucous membrane of the canal, having 
forced their way probably through the lymph-follicles and Peyer’s patches, as Koch 
supposes. From hence the way is open through the capillaries into the blood-. 
passages. 
According to Koch’s investigations the infection comes much more frequently 

1 Bot. Centralblatt, 14, p. 315. 
