Abstract
The particular phenomenon observed in the trachea of the germfree animals exposed to the air containing silica particles was the invasion of the particles into the epithelial cells and the subepithelial layers. In conventional animals, no invasion was noticed. Sulfur dioxide gas of 40ppm impeded preventive functions of mucous membrane of the animals both in germfree and conventional, involved in removing the extraneous substances and bacteria. Basic pathogenic changes in the lungs of germfree guinea pigs under the influence of SO2 gas or of Staphylococcus aureus 209p infection were interstitial inflammation in the circumferential alveolar septa around the bronchioles and capillaris. Changes in the lungs of germfree animals affected by SO2 gas with a combination of bacteria were modified by superimposed brochopneumonia following numerical changes of bacteria in the lungs.
