A Paper on “Three Forms of Bacilli,” was read by Dr. J. Mitchell Wilson.
Dr. Wilson introduced his subject as a continuation of a paper upon “Germs” read to the Society seven years ago. Since that time enormous advances have been made in the study and special exertion of every form of Micro-organism.
After defining the micrococcus, the bacillus, and the spirillum, the reader said his paper would deal with three forms of the bacillus only. Bacilli are minute vegetable cells without a nucleus, they multiply by fission; the granular contents have the power of retaining dyes and from this observers are assisted in distinguishing several varieties of the bacillus. Some forms have the power of spore formation, and bt this means the germ increases at a very rapid rate. Further, the spores are able to withstand greater degrees of heat and cold, and stronger chemical action than the adult bacillus. Spores can only be formed where there is an ample supply of oxygen and moisture, and cannot be formed below 120 or over 440 Boiling for less than 10 minutes does not destroy the spore nor any known degree of cold.
Bacilli are recognised in two main groups non-pathogenic or harmless, and pathogenic or associated with some form of diseased state. The three forms considered were the Bacillus-subtilis or hay Bacillus, the Bacillus-anthrax, or that form associated with splenic fevers, and the Bacillus-tuberculosus or that form associated with tubercle, The bacillus subtills is a variety of the group of septic bacteria or those associated with putrefaction; they do not produce any clearly defined form of illness in the animal body. They are largely concerned with splitting up of decaying organic matter into simple inorganic elements, this action is, however, often accompanied by the formation of an alkaloid “sepsis” which may re-act as a poison on the animal body. The theory that the Hay bacillus was under certain conditions convertible into Anthrax bacillus and vice versa was proved to be untenable.
The Anthrax Bacillus is the cause of splenic fever in animals, and the wool sorter’s disease in man. The bacillus is known to be introduced into this country among the wool and hair of animals which have died of Anthrax. It can be artificially cultivated in many nutrient media. A description was given of the methods adopted in making such cultivations, and the proofs required before admitting any form of bacillus as the cause of disease. Pasteur’s work in protecting sheep against splenic fever by attenuated or weakened virus was referred to, and the means now being adopted to protect wool sorters by disinfecting the fleeces.
The bacillus tuberculosus was first discovered by Koch, of Berlin, in the sputum of persons and animals suffering from tubercles. It measures from one seven thousandths to one eleven thousandths of an inch in length, and therefore requires the highest powers of the microscope for the detection. That work is greatly assisted by the action of various colouring or staining solutions. The presence of this micro-organism in the milk or flesh of animals generally used as food was discussed as a matter of preventive medicine.