NEK VE- TISSUE. 1 1 / 



then with two alcohols, cleared in oil of cloves, and 

 mounted in balsam. 



The axis cylinders, neurilemma, Ranvier's constrictions, 

 incisions of^Schmidt, neurilemma nuclei, and neuroglia 

 cells are stained red. 



Transverse Sections of Nerves Stained with Osmic Acid. 

 A nerve treated as above with osmic acid is not firm 

 enough to permit the making of thin sections, and should 

 be imbedded by the celloidin paraffin method (see page 

 17). The sections (which must be very thin) are mounted 

 in balsam. In such a preparation the uncolored axis 

 cylinder is seen surrounded by a black ring, the medullary 

 sheath, and here and there the nuclei of the neurilemma 

 are seen at the edge of the fibres. The connective tissue 

 surrounding the fibres has a grayish color. The nerve- 

 fibres will be seen to have varying diameters and to pre- 

 sent marked differences in form, some of them depending 

 upon artificial changes, others upon the difference in level 

 at which the fibres have been cut across. 



Transverse Sections of Nerves Preserved in Chromic 

 Acid. Bits of the sciatic nerve from the rabbit or any 

 other mammal should be lightly stretched along a bit of 

 wood and placed in a solution of chromic acid (i to 500); 

 in two weeks it is washed and transferred to alcohol. It 

 is now imbedded in celloidin, and thin transverse sec- 

 tions made and stained double and mounted in balsam. 

 In such preparations the general relation of connective 

 tissue to the nerve-fibres is well seen. 



Nerve-fibres Treated with Nitrate of Silver. By this 

 method we obtain hints concerning the structure of nerves 

 which are of no little significance from a physiological 



