THE MYELINS : THEIE PROPEETIES 171 



fact that by alcoholic extraction similar bodies could be gained 

 from other tissues : from the blood, from yolk of egg, from the 

 ovaries of calves, from the normal spleen, goitrous thyroid and 

 diseased lungs. And, as in their physical properties they 

 resembled brain marrow, Virchow gave these the class name of 

 myelin. Whether he was dealing with one or with several 

 substances, he could not determine ; he was inclined to the 

 view that, if not a single substance, he dealt with a group which 

 chemically were as closely allied as the various albumins. And 

 Virchow summed up their properties as follows : 



1. When brought into contact with water they swell up, 

 and in doing so exhibit a characteristic morphology, being seen 

 under the microscope to develop processes of irregular and 

 often bizarre form, globular, rod-like, or curved on themselves 

 and variously distorted, exhibiting, as already noted, a double 

 contour, undergoing changes of shape while under examination. 



2. They are easily soluble in hot alcohol, becoming, in part, 

 precipitated on cooling. 



3. They dissolve rapidly in ether, chloroform, and turpentine. 



4. They are acted on but slowly and to a slight extent by 

 weak acids and alkalies. 



5. Under the action of strong alkalies they shrink, with 

 eventual loss of their characteristic properties. 



6. Under the action of strong acids they first swell greatly 

 and then undergo dissolution. 



Now, whether recognizable immediately in the tissues or cells 

 or cell debris so soon as water is added, or recognizable only 

 after an alcoholic extract has been made of the tissues and such 

 extract treated with water, bodies conforming to these postu- 

 lates have been found distributed through the organism. And 

 as a class they possess, with the limitations already laid down, 

 the power of double refraction. 



The history of the recognition of this last property affords 

 an interesting example of the way in which valuable observa- 

 tions may, for long years, wholly disappear from remembrance, 

 and that because they have been originally given to the world 

 in the pages of an obscure journal. In 1857, if I mistake not, 

 a society was established in Germany for the advancement of 

 medical science, and the official organ of that association was 

 distributed primarily, and it would seem almost entirely, among 



