68 JOURNAL OF THE [July, 



the nerve system. In the gray substance, again, we meet with 

 innumerable protoplasmic bodies, the so-called "ganglion cells," 

 or ganglionic elements, from which, as is to-day generally con- 

 ceded, arise the nerves proper in the shape of so-called axis 

 cylinders. All these bodies, therefore, are unquestionably cen- 

 tral organs. In analyzing the ganglionic bodies we see them 

 composed of a dense, delicate reticulum, first recognized by C. 

 Frommann, of Jena, in 1867. Each ganglionic body sends out a 

 thread-like prolongation, the axis cylinder, and a varying number 

 of branching offshoots, termed, in honor of their discoverer, Die- 

 ters' offshoots. All the latter run into the gray substance at large, 

 and only the axis-cylinder offshoot is a nerve, running from the 

 central ganglion uninterruptedly to the periphery of the body. I 

 exhibit such a body with a power of 500 diameters, fully sufficient 

 to recognize the offshoot, though not the central reticulum. 



Again, the gray substance is made up of a tiny reticulum of liv- 

 ing matter, not quite as dense as that of the ganglionic elements. 

 I was the first to discover this reticulum in perfectly fresh sec- 

 tions of the brain of just killed rabbits, twenty years ago ; but 

 this is an assertion of mine that has not as yet met with the con- 

 firmation of other microscopists. The reticulum is easily made 

 visible by a stain with osmic acid, as shown here, with a power 

 not exceeding 300 diameters. This reticulum is connected with 

 all the Dieters' offshoots of the ganglionic elements, and again 

 sends out axis cylinders, the same as do the ganglionic elements. 

 This my assertion has recently found corroboration by Edinger, 

 of Germany. 



It is plain that contraction, originating in the ganglionic ele- 

 ments, will be conducted partly to the gray substance by the off- 

 shoots of Dieters, and partly to the periphery through the axis- 

 cylinder offshoot, the nerve proper ; for the structure of the 

 latter is reticulated the same as is that of the ganglionic bodies 

 and the gray substance in general. 



Many facts, obtained either by experiments on animals or by 

 observations in morbid changes of the brain, have led us to the 

 conviction that the ganglionic elements are the seat of all our 

 knowledge, called positive, brought into our brain from without 

 by the organs of sense. Such a positive knowledge is, for in- 

 stance, the a, b, c by means of which we read and write, the 



