27 "Antiseptica und Bacterien," Arch. f. exp. Pathol. und Pharmakol., Bd. iv., Heft 1 und 2.
It is, however, from the constant presence of the bacteria in infected wounds, and their distribution through the tissues, that the argument in favor of connecting septic symptoms with the bacteria has been mainly deduced. Here the ground is sufficiently solid, and, judged by ordinary laws of scientific evidence, the pathological importance of the microspores may be regarded as established. To be sure, we find them in tongue-scrapings of healthy individuals, but tongue-scrapings are poisonous if injected into the tissues. That they do not ordinarily prove so in the mouth is no more singular than that woorari can be swallowed with impunity. Tiegel28 has endeavored to show that round bacteria are found normally in the internal organs of the body; but Koch29 states that he has on many occasions examined normal blood and normal tissues by means which prevented the possibility of overlooking bacteria, or of confounding them with granular masses of equal size, and that he has never in a single instance found organisms.
28 Arch. f. Path. Anat. u. Physiol. u. f. klin. Med., vol. lx. p. 453.
29 On Traumatic Infective Diseases, New Sydenham Soc. publication p. 15.
It is stated that bacteria are sometimes absent from the blood withdrawn during life in septic diseases. As, however, their constant presence has been confirmed in the vessels and glomeruli of the kidneys, it is fair to assume that those organs, acting as filters, must have received the colonies observed in them from the general circulation.
The difficulty of obtaining bacteria from the blood in many cases during life in septic diseases does not, however, as was once supposed, invalidate the theory of their pathogenic importance. Septicæmia is at present employed as a collective term for a number of processes which may occur singly or in combination with one another. When a relatively large quantity of a putrid fluid is injected into the veins of an animal, death follows from the action of a chemical poison (sepsin). The blood during life rarely displays the presence of bacteria, the latter disappearing in the circulation. In animals thus poisoned blood does not possess infectious properties. This form is termed putrid intoxication. That the poison in these cases is, however, produced by the bacteria is shown by experiments of Gutmann,30 who demonstrated that bacteria from a drop of putrid blood cultivated in Cohn's solution developed in the fluid a poison which, when injected into the veins of dogs, occasioned death with all the symptoms of putrid intoxication. Still more conclusive were the experiments of Koch. This observer injected four drops of putrid blood beneath the skin of mice. The latter died in from four to eight hours. There were no bacteria in the blood, and the blood was not infectious. When, however, a single drop was injected, the mice often remained unaffected, but in a third of the cases they became ill after twenty-four hours, death occurring in from forty to sixty hours. The blood during life communicated the same disease to other mice, and bacilli were always present in large numbers. In these cases the dissolved poison in the fluid injected was too small in amount to destroy life, and death resulted only after a period of incubation as a consequence of the multiplication of bacilli in the blood and in the tissues.
30 Vide Semmer, "Putride Intoxication," etc., Virchow's Arch., vol. lxxxi. p. 109.
In another class of cases Koch experimented, not with putrid blood, but with a fluid produced by macerating a piece of mouse-skin in distilled water. Of this he injected a syringeful into the back of a rabbit. The result was peritonitis, swelling of the spleen, gray wedge-shaped patches in the liver, and in the lungs were found dark-red patches the size of a pea, devoid of air—all appearances in harmony with what is designated as pyæmia. Oval micrococci were found in great numbers everywhere throughout the body. But the point of special interest in the present connection is the fact that wherever these micrococci come in contact with the red blood-corpuscles the latter stick together and become arrested in the minute capillary network. The thrombi thus formed are further enlarged by the deposition of micrococci, which multiply, block up individual capillary loops, and invade contiguous tissues. In the blood-current itself, however, the micrococci do not increase in numbers, and cannot always be found in the circulation upon a single examination, but Doléris31 assures us that in puerperal fever by repeated trials, especially after a chill, he has never failed to demonstrate their presence.
31 La Fievre Puerperale, etc., p. 120.
As to the exact manner in which these minute bodies exercise their pernicious influence, whether they operate mechanically, or whether they produce a virus in the process of nutritive activity, or whether, as is probable, both suppositions are correct, must be decided by future investigations. It is enough for us to note that the connection between sepsis and bacteria is intimate and vital.