270 LECTURE XI. 



Now it is very remarkable that this same substance is one 

 which most extensively prevails in the animal body. I 

 had, curiously enough, in the first instance in the exami- 

 nation of lungs come across forms which presented very 

 similar qualities to those which we observe in the me- 

 dulla of the nerves. Although this was very surprising, 

 yet I did not really think there was an actual correspond- 

 ence, until I was gradually led by a series of further ob- 

 servations which accumulated in the course of several 

 years, to examine a number of tissues chemically. The 

 result showed, that there scarcely exists a tissue rich in 

 cells in which this substance does not occur in large 

 quantity ; still it is only in the nerve -fibre that we ob- 

 serve the peculiarity, that the 

 substance separates as such,whilst 



00 - A B in all other cellular parts it is 



S\ 1 @ *? ,' contained in a nnel 7 divided state 

 /*?<Hl ^ iff * n ^ e m ^ er i r f t ne cells, and is 

 * @ only set free when the contents 



undergo a chemical change, or are subjected to the action 

 of chemical reagents. From blood-cells, from pus-cor- 

 puscles, from the epithelial cells of the most various glan- 

 dular parts, from the interior of the spleen and similar 

 glands unprovided with excretory ducts, this substance 

 can in every case be obtained by extraction. It is the 

 same substance which forms the principal constituent of 

 the yellow mass of yolk in the hen's egg, whence its taste 

 and peculiarities, especially its peculiar tenacity and vis- 

 cidity which are employed for the higher technical pur- 

 poses of the kitchen, are familiar to every one. It is this 

 substance, for which I have proposed the name of medul- 



Fig. 80. Drops of medullary matter (myeline according to Gobley, lecithine). 

 A. Differently shaped drops from the medullary sheath of cerebral nerves, after they 

 have become swollen up with water. B. Drops from decomposing epithelium from 

 the gall-bladder in their natural fluid. 300 diameters. 



