170 ON VARIABILITY AND ADAPTATION 



science it leads, and to set you guessing, and I hope some of 

 you more than guessing, as to what is the conclusion thereof. 

 For the matter appears to open up not a few lines of profitable 

 investigation. I may, it is true, give you immediately an ap- 

 parent answer. I can, that is, give these bodies a name. I 

 may call them " myelin globules," and state that they are the 

 condition assumed by myelin at a certain phase or under certain 

 conditions. I question, though, whether this will bring much 

 comfort. For what is myelin ? 



The remarkable fact about myelin is that it has been known 

 for more than fifty years ; that within a few years of its recog- 

 nition by Virchow, in 1854, it had been determined that bodies 

 of the nature of myelin could be gained from practically every 

 organ of the body, and this often in large amounts, and that, 

 though this is the case, though the pains of pathologists brought 

 myelin into the world and pathologists mothered, or fathered, 

 it, though there is quite an extensive literature on the subject, 

 it is rarely mentioned in polite medical society. Your writers 

 of text-books on physiology and pathology studiously pass by 

 on the other side without apparent recognition of its existence. 

 This possibly because, had they recognized its existence, they 

 could but confess their ignorance why it was there and what its 

 function in the economy. And it has to be confessed that myelin 

 has shown itself a most elusive substance. 



If one takes fresh medullated nerve or brain substance and 

 teases it out in water, the marrowy matter forms into drops 

 and masses of irregular rounded contour, and as one examines 

 these they become altered in shape, throwing out blunt rounded 

 processes with a double contour. We are clearly not dealing 

 with ordinary fats. Early in the last century Berzelius ob- 

 served that the cerebrin which he extracted from brain matter 

 gave similar bizarre forms ; so, too, Drummond, in 1852, noted 

 a like phenomenon with the alcoholic extract of brain matter. 

 I find, indeed, that if fresh brain matter be placed in absolute 

 alcohol for twenty-four hours the development of these bodies 

 and processes becomes greatly exaggerated. Place a fragment 

 under a cover-slip and surround with water, and long processes 

 are shot out from the mass, curving in a most serpentine and 

 life-like manner, and from them double contoured droplets 

 become detached. Virchow, in 1854, called attention to the 



