204 THE INFECTIOUS DISEASES. 



the pia mater, and the connective tissue in different parts of the body 

 may be inflamed. These local inflammations are usually purulent, ex- 

 cept in the serous membranes, where the principal inflammatory product 

 may be fibrin (Fig. 89). The veins in the neighborhood of the wound 

 may contain softened, purulent thrombi, without infarctions in the vis- 

 cera while there may be inflammation of the joints and serous membranes. 

 On the other hand, with the venous thrombosis there may be infarctions 

 and abscesses in the viscera; local inflammations of the joints and serous 

 membranes may be present or absent. While thrombi are often formed 

 in the veins near the wound, they may be situated in A T eius at a distance, 

 and sometimes, although infarctions and abscesses be present, no thrombus 

 can be discovered. The veins may be distended by the thrombi or contain 

 only small coagula. The different kinds of thrombi, and the varieties 

 of emboli and infarctions which they produce, are described in the section 

 on Thrombosis, p. 72. Leucocytosis usually accompanies pyaemhi and 

 septicaemia as well as the suppurative process with which they are asso- 

 ciated. Studies of the blood in various forms of septicaemia are numerous 

 and instructive, but we cannot consider them here. ' 



Various lines of research on minute changes in cells which bacterial 

 and other poisons may induce justify the expectation that more and 

 more we shall be able to associate characteristic groups of symptoms in 

 toxaemia and septicaemia for which there is now no morphological basis, 

 with well-defined cell alterations. Among the most striking of the toxic 

 cell lesions thus far studied in septicaemia and bacterial toxaemia are those 

 involving the cytoplasm of the ganglion cells (see Xervous System). 



THE PYOGENIC BACTERIA. 



While many species of microbes are capable under favorable condi- 

 tions of inciting suppuration and other forms of exudative inflamma- 

 tion and may when they or their toxins are disseminated in the body 

 give rise to toxaemia, septicaemia, and pyamia, there are two forms 

 which, on account of their early discovery and their relative frequency, 

 are commonly considered as par excellence " pyogenic " bacteria. These, 

 which are called StapJtylococcus and Streptococcus, we shall consider first. 



CHARACTERS OF STAPHYLOCOCCUS PYOGENES. 



The Staphylococcm pyoyenes aureus (Micrococcus pyogenes aureus) (Fig. 95) is a 

 relatively small coccus, the individuals varying, however, considerably in size (0.7 to 

 1.2 n in diameter). In its growth it does not show a characteristic grouping, but grows 

 in irregular masses and heaps (the somewhat crude resemblance, when studied under 

 a cover glass, to a bunch of grapes gave rise to the generic name) ; sometimes, however, 

 pairs and groups of four or short rows of the cocci are seen. The germ is readily stained 

 by the anilin dyes, and does not lose its color in Gram's method of staining. It does 



1 Consult White, Journal of Experimental Medicine, vol. iv., p. 425, 1899; also: 

 Adami, Journal of the American Medical Association, December 16th and 23d, 1899. 

 Both have bibliography. 



