C. L. HOAGLAND 



of its specialized architecture, a fairly satisfactory comparison can be 

 made between structures revealed in ultraviolet light and those which 

 are observed after staining and photomicrography in the visible region 

 of the spectrum. Not only is greater resolution achieved with ultra- 

 violet light photography, but the image which is obtained may provide 

 in addition some idea of the chemical nature of the absorbing areas of 

 the tissue, since it results from the selective absorption of light by 

 proteins and by substances of high absorptive capacity, such as the 

 purines and pyrimidines. 



A plethora of micro methods is available for the quantitative 

 determination of tissue constituents, and for almost every type of inter- 

 mediary compound known to arise in metabolism. However, inter- 

 pretation of quantitative data secured by analysis of diseased muscle 

 is enormously complicated by lack of information concerning the total 

 mass of muscle cells in these specimens due to their variable content 

 of fat, fibrous connective tissue, collagen, and water. It may be 

 highly desirable to determine quantitatively the various mineral con- 

 stituents of diseased muscle, and to analyze the material for its content 

 of creatine, adenylic acid, and various organic esters of phosphorus. 

 The results have little significance, however, unless some suitable basis 

 of reference can be found which will permit comparison of the mass 

 of muscle cells in one specimen with the mass of cells in another. 

 Two specimens of muscle removed at biopsy from approximately the 

 same area, in a subject showing incipient progressive muscular dys- 

 trophy, may show differences of 50% in fat content, 20% in concen- 

 tration of collagen and fibrous connective tissue, and 15% in the 

 content of free water and ash. Low values for creatine phosphate, 

 adenosine triphosphate, or other organic constituents in specimens of 

 diseased muscle have little significance unless some factor of correction 

 can be employed which will allow for the differential mass of muscle 

 cells present in the samples. Some success was achieved recently in 

 our laboratory in the use of myosin as a base of reference for certain 

 organic constituents of diseased muscle. Since myosin is the principal 

 protein component of the contractile cells of muscle, its concentration 

 must bear an important quantitative relationship to the total mass of 

 contractile cells in the specimen taken for analysis. Owing to its 

 property of critical solubility in potassium chloride, myosin can be 

 determined quantitatively, and with a fair degree of accuracy, on, 



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