4: LECTURES ON THE CENTRAL NERVOUS SYSTEM. 



carmine. As time passed on, many new staining methods were 

 devised, particularly with aniline colors (nigrosine, etc.). 



But it is only very recently (1883) that we have learned 

 from Golgl a method which brings out ganglion-cells more dis- 

 tinctly than the old one of Gerlach. This method rests on the 

 production of a deposit of silver salts in the cells and their 

 processes. The course of the fibres in the central nervous 

 system is not made much more distinct by staining with car- 

 mine. It is possible, however, by a method of staining with 

 hsematoxylm introduced by Weigert (1884), to color even the 

 finest nerve-fibril a deep blue-black, and so, making use of 

 Stilling's method, it is easy to trace the course of the fibres 

 much farther than was formerly possible. 



The stained sections are, in accordance with the special 

 instructions of Clarke (1851), dehydrated by placing them in 

 alcohol, and then cleared up in some ethereal oil or xylol. 

 But unstained sections also reveal the course of the fibres if 

 cleared up in xylol, as was done by Henle and Merkel. This, 

 however, does not always succeed. Beautiful pictures may be 

 obtained by using the gold staining methods (Gerlach, Flechsig, 

 Freud, and many others). Also, by staining the nerve-fibres 

 with osmic acid (Exner). 



Stilling's method has been followed by most of the investi- 

 gators of the latter half of this century. At the close of each 

 lecture I will give you the names of those to whom we are in- 

 debted for the most important part of our knowledge of that 

 portion of the brain which is under consideration at the time. 

 But even now you must be made familiar with the names of 

 two men, Stilling and Meynert, to whom we are under the 

 greatest obligations, because to them we owe our knowledge of 

 the finer structure of the brain and spinal cord, and all the later 

 investigators start out from points which have been settled by 

 them. 



Benedict Stilling laid the foundations of our knowledge of 

 the anatomy of the pons, the cerebellum, the medulla oblongata, 



