34 
HOWARD B. FELTON. 
defense of the epidermis. The skin also contains glands pro¬ 
ducing sweat and oily matter. These substances are eminently 
unfavorable for keeping up life in microbes. Should the mi¬ 
crobes penetrate into the glands themselves, they are borne out 
upon the current of gland secretion when the gland is excited 
into action. Those microbes which enter the mouth and nos¬ 
trils, find a membrane lining there composed of cells not unlike 
the cells of the epidermis, and this membrane is constantly 
moistened with liquids which are not at all favorable to the de¬ 
velopment of the assailant. If the microbes manage to get into 
the oesophagus and so reach the stomach they find there condi¬ 
tions which are not good for their health in the shape of chloro- 
hydric, lactic and other acids.” 
According to Escherich the bacillus lactis serogenes is found 
normally in the stomach and is responsible for the conversion of 
milk sugar into lactic acid, which is a powerful germicide for 
the other forms of bacteria. “ Many microbes are absolutely in¬ 
capable of getting through the stomach and penetrating into the 
intestines, for they have been so battered and knocked about and 
their vitality has been so much lowered by their troubles on the 
road that they end by being destroyed and even digested in the 
stomach. It has been proved, however, that mucous surfaces 
are not always an obstacle to the penetration of the microbes 
even when these surfaces are intact. Suppose the microbes 
manage to penetrate the tissues, then they meet with new ob¬ 
stacles. They find in the first place what are called phagocytes 
—that is, cells which are eaters. These elements of the lymph 
show surprising activity, swallowing the microbes and digesting 
them. These phagocytes are most abundant at threatened 
points. If in spite of the phagocytes, the microbes get into the 
blood, they have not won the battle yet. The serum of the 
blood has microbe-killing properties. The oxygen that is car¬ 
ried into the blood disagrees with many of the microbes, as 
carbonic acid does with others, and thus it is that the blood is 
rarely invaded with microbes in the course of the maladies they 
engender. If the microbes take up their residence in the heart 
