The limitations in the use of the term hyaline degeneration are but ill defined. On the one hand, there is included the transformation of muscular tissue, first discovered by Zenker; on the other, the various changes described by Recklinghausen and others, among which are embraced the results of Wagner's croupous metamorphosis. As the hyaline appearances are a frequent result of coagulative necrosis, these terms are frequently used to indicate the same condition, according as the optical or etiological features are uppermost in the mind of the observer. The hyaline or waxy degeneration of muscular fibre described by Zenker represents a metamorphosis of the protoplasm of striated muscle in particular, although the fusiform cells of the muscular coat of the stomach and intestine may present a similar transformation. The microscopic appearances are more characteristic than those visible to the naked eye. To the latter the muscle appears paler, more translucent, and homogeneous, and proves to be more brittle than normal. The muscular fibres are found with the microscope to be swollen, irregular in outline, the myosin transformed into flaky, glistening masses, without evidence of the normal transverse striation. These appearances have given rise to the term waxy degeneration, which suggests a possibility of confusion with the earlier recognized waxy degeneration of organs, due to the presence of amyloid material. The waxy transformation of muscular fibre, however, does not present the reaction with iodine characteristic of amyloid substance. The degeneration of the muscle is usually regarded as the result of a coagulation of the myosin, and it is claimed by Cohnheim that the latter takes place only in dead muscle, either during the life of the individual or as a post-mortem appearance. The hyaline degeneration of muscular fibre is found in certain febrile diseases, as typhoid and typhus fevers, scarlatina, variola, and cerebro-spinal meningitis. It may also be met with when a muscle has been exposed to violence, as in the insane who have been placed under mechanical restraint. It has further been found in the vicinity of tumors, especially where muscles have been invaded by their growth. Cohnheim and Weil describe a similar condition in the tongue of frogs after ligature of the lingual artery. The pathological importance of the above-mentioned degeneration of muscle is most prominent in cases of typhoid fever. The occurrence in this disease of the hæmatoma or blood-tumor of the rectus abdominis is thus explained, the degenerated muscle and its contained blood-vessels being ruptured. The muscles of the thigh and the diaphragm frequently undergo this degeneration; the change is more rarely met with in other muscles of the body.