H valine Pc\i:;ciicratioii. 20i 



ber of similar but not identical albuminates. There are minor dif- 

 ferences recognized among the different examples in the staining 

 reactions, which indicate this multiplicity, but as yet it is impossible 

 to indicate a clear basis of separation. As a result of this uncer- 

 tainty, however, there have arisen a number of types tentatively 

 spoken of as forms of hyaline degeneration. Thus, the hyaline met 

 in dense connective tissues as scars, walls of sclerotic blood vessels, 

 etc., is usually regarded as the typical form, the fibrous tissue here 

 forming minute or grossly visible masses of the glassy transparent 

 matter, and grossly presenting an appearance very similar to hya- 

 line cartilage, the material being of about the same consistency 

 as the latter. Another form is met in tuberculous and syphilitic 

 lesions as a precursor of the later caseous change ; it is spoken of 

 as a "necrotic hyaline" and is apt to exist only in microscopically 

 appreciable amounts, but under the microscope presents the same 

 general appearances as the typical variety. In muscle a hyaline 

 change minutely distinguishable by the uniform alteration of the 

 muscle fibre into a homogeneous, glassy, cylindmid area or by the 

 formation of lumps of such a material within the fibre, and occa- 

 sionally extensive enough to give the tissue, when grossly examined, 

 a peculiar boiled appearance, is met in typhoid fever (Zenker's 

 hyaline degeneration) in man. in the hsemoglobinsmia of horses, 

 and in a variety of infectious diseases and local inflammatory 

 changes in muscle in various forms of animal life. This variety 

 closely resembles coagulation necrosis. In the blood a variety of 

 hyaline thrombi, usually minute and representing the primary forma- 

 tion of the clot, is due to a fusion of blood plaques or of blood 

 plaques and leucocytes ; and in old clots a change often spoken of 

 as "blood hyaline," leading to more or less homogenization of the 

 cellular and fibrinous constituents of the clot into a transparent, 

 structureless and yellow-colored (microscopically) or reddish 

 (grossly) material. Definite fibrinous exudates, as that of pleurisy 

 or pericarditis, and that of false membranes, as of diphtheria, 

 sometimes undergo a similar change (exudative hyaline), losing 

 all the reticular appearance of the earlier stages and presenting 

 uniformly glass-like sheets or bands or clumps of hyaline matter. 

 Within tumors, especially sarcomata, hyaline matter is often found ; 

 in some of the sarcomata mantles of the substance form over the 

 blood vessels or actually involve the vessels and render them im- 

 pervious (cylindromata). In various changes and in various situa- 

 tions in the body, rounded, spheroidal, minute masses, often show- 



