KN TRANCE AND SPREAD OF BACTERIA 213 



though tliis is difficult of proof, as it is much increased in 

 numbers in practically all abnormal conditions of the intestine. 

 We may ivmurk that it has been repeatedly proved that the 

 bacillus coli cultivated from various lesions is more virulent than 

 that in the intestine, its virulence having been heightened by 

 growth in the tissues. 



The micrococcus tetrayenus is often found in suppurations in 

 the region of the mouth or in the neck, and also occurs in 

 various lesions of the respiratory tract, in phthisical cavities, 

 abscesses in the lungs, etc. Sometimes it is present alone, and 

 probably has a pyogenic action in the human subject under 

 certain conditions. In other cases it is associated with other 

 organisms. Cases of pyaemia have been described in which this 

 organism was found in a state of purity in the pus in various 

 situations. In this latter condition the pus has been described 

 as possessing an oily, viscous character, and as being often 

 blood-stained. 



The bacillus pyocyaneus is rarely found alone in pus, though 

 it is not infrequent along with other organisms. We have met 

 with it several times in cases of multiple abscesses, in association 

 with the staphylococcus pyogenes aureus. Lately some diseases 

 in children have been described in which the bacillus pyocyaneus 

 has been found throughout the body ; in these cases the chief 

 symptoms have been fever, gastro-intestinal irritation, pustular 

 or petechial eruptions on the skin, and general marasmus. It 

 has also been said to be constantly present in pemphigus, and 

 it certainly occurs in some cases of this disease. 



Inflammatory and suppurative conditions, associated with the 

 organisms of special diseases, will be described in the respective 

 chapters. 



Mode of Entrance and Spread. Many of the organisms of 

 suppuration have a wide distribution in nature, and many also 

 are present on the skin and mucous membranes of healthy 

 individuals. Staphylococci are commonly present on the skin, 

 and also occur in the throat and other parts, and streptococci 

 can often be cultivated from the secretions of the mouth in 

 normal conditions. The pneumococcus of Fraenkel and the 

 pneumobacillus of Friedlander have also been found in the 

 mouth and in the nasal cavity, whilst the bacillus coli communis 

 is a normal inhabitant of the intestinal tract. The entrance of 

 these organisms into the deeper tissues when a surface lesion 

 occurs can be readily understood. Their action will, of course, 

 be favoured by any condition of depressed vitality. Though in 

 normal, conditions the blood is bacterium-free, we must suppose 



