MYOCARDITIS. I49 



sections through its walls appear yellowish-red, marked with patches 

 or stripes of a lighter colour. Examined microscopically, the fibres 

 are seen to have lost their striation, and to be more or less infiltrated 

 with proteid granulations, broken up and partially destroyed. In 

 addition, there is often a slight increase in quantity of connective tissue. 



These lesions are found irregularly distributed in both hearts, but 

 especially in the thickness of the septum and of the wall of the left 

 ventricle. They may be little marked at certain points, while well 

 developed, or even of old standing, in others. Cases occur where the 

 quantity of new connective-tissue growth is very small, and where the 

 process appears to consist essentially in simple granulo-fatty degenera- 

 tion of the muscular fibres. 



In fibrous or sclerosing myocarditis, by far the most common form, 

 the heart may be hypertrophied, of normal volume, or more or less 

 atrophied. When increased in size the hypertrophy must not be 

 ascribed to the myocarditis ; it has preceded the latter, having resulted 

 from excessive functional activity of the muscular tissue, necessitated 

 by the presence of some obstruction to the free circulation of blood. 

 The heart's surface is marked with irregular depressions, corresponding 

 to portions of the cardiac muscle which have undergone fibrous trans- 

 formation, followed by contraction of the new connective tissue. The 

 sclerosis is of varying depth and area. In a general sense it is always 

 of vascular origin, resulting primarily from proliferation of the cells 

 forming the walls of small vessels, and gradually" extending to the 

 interfascicular tissue, producing fibrous new growths, which afterwards 

 compress and destroy the true muscular fibres. This cardiac sclerosis 

 is sometimes periarterial, related to arterio-sclerosis, sometimes peri- 

 venous, due to stasis produced in the last period of valvular disease, 

 and peculiar to what M. Huchard has called in man " cardiac heart." 

 Microscopic examination reveals patches, bands, and anastomosing 

 networks of fibrous tissue, of varying size, between the muscular fibres, 

 many of which, in consequence of their pressure, have undergone 

 degenerative changes or have altogether disappeared. 



The changes due to myocarditis when accompanying endocarditis 

 or pericarditis, and developed by contiguity of structure, sometimes 

 extend to the entire cortical layer of the muscle ; the latter showing on 

 section a zone, several millimetres in thickness, of a reddish pale }ellow 

 or whitish tint, depending on the stage and form of the disease. In 

 this layer the muscular fibres have undergone granulo-fatty degenera- 

 tion, or have become atrophied by pressure of the new tissue and 

 fibrous networks. Instead of thus being spread over the entire surface 

 of the myocardium, the lesions are in many cases circumscribed. In 



