CHAPTER IV 



THE MYELINS AND POTENTIAL FLUID CRYSTALLINE 

 BODIES OP THE ORGANISM x 



(1906) 



THE polarizing microscope, simple as it is with its Nicol's prisms 

 the two pieces of Iceland spar which can be turned at various 

 angles one to the other has not been a popular instrument in 

 medical science. I take it that my own experience is that of 

 other medical men. I can remember well a genial and enthusi- 

 astic colleague inviting me years ago to spend the evening with 

 him, when he showed me slide after slide of various substances 

 exhibiting exquisite figures under the Nicol's prisms. I know 

 I thought the results too pretty to be useful that the instrument 

 was peculiarly well adapted for the use of members of microscopic 

 societies and other amateurs of microscopy, but for the physician 

 and pathologist it was at most a toy. I would here recant this 

 early error and would acknowledge humbly that within certain 

 limits the polarizing microscope shows itself a most valuable 

 aid in the detection and recognition of the nature of a class of 

 substances within the tissues which it is difficult, nay almost 

 impossible, to recognize by other means. 



If you take a section of the fresh adrenal of man or of one 

 of the animals of the laboratory and examine the cortex under 

 the ordinary microscope, the parenchyma cells have, as is well 

 known, the appearance of being in the condition of advanced 

 fatty degeneration the cell substance, that is, is seen to be 

 densely packed with small fatty globules. But, as shown by 

 Kaiserling and Orgler, examine that section between the Nicol's 

 prisms, and sundry of the globules exhibit an exquisite black 

 1 Lecture delivered before the Harvey Society, New York, December 1, 1906. 



