10 Structure op Neurones in Nervous System of White Rat 



drawn from that of the new-born white rat having a body-weight of 4. 5 grams. For con- 

 venience the axones are represented in red, while the dendrites are in yellow. Although 

 the olfactory glomeruli are of very complicated structure, owing to an intricate arrange- 

 ment of the two kinds of the processes, yet, after knowing the character of the axone 

 and dendrite as determined by the neurosomes in them, one can easily see that in 

 many cases a single long and apparently continuous filament is composed of two dif- 

 ferently characterized parts ; that is, the neurosomes in one portion are much larger 

 and stain more deeply than those found in the other portion. In other words, these 

 apparently continuous lines are composed of two different structures, the axones and 

 the dendrites. In the case of the glomeruli in the granular layer of the cerebellar 

 cortex, continuous filaments formed from two sorts of processes, as observed in the 

 olfactory glomeruli, were not found, but a mere contiguity of the two processes, such 

 as is noticed in the dendrites of the Purkinji cells and the axones which surround them, 

 was all that could be observed. 



GENERAL REMARKS 



The history of the investigations on the neurone has been beautifully summar- 

 ized by Goldscheider and Flatau (1898), Barbacci (1899), Barker (1899), Robertson 

 (1899), Soury (1899), and Van Gehuchten (1900), but in order to show the bear- 

 ing of our own observations, it will be necessary briefly to review the more important 

 theories concerning the neurone. 



According to the most prevalent view, the "neurone" or the nerve-cell with all 

 its processes may be regarded as an independent element, from the anatomical stand- 

 point; consequently the entire nervous system is an aggregation of those independent 

 elements. This view was first brought out by Waldeyer (1891). He says: 



Das Nervensystem besteht aus zahlreichen untereinander anatomisch wis genetisch nicht 

 zusammenhangenden Nerveneinheiten (Neuronen). Jede Nerveneinheit setzt sich zusammen 

 aus drei Stiicken: der Nervenzelle, der Nervenfaser und dem Faserbaumchen (Endbaumchen). 

 Der physiologische Leitungsvorgang kann sowohl in der Richtung von der Zelle zum Faser- 

 baumchen als auch umgekehrt verlaufen. Die motorischen Leitungen verlaufen nur in der Rich- 

 tung von der Zslle zum Faserbaumchen, die sensiblen bald in der einen, bald in der anderen 

 Richtung. 



This view of Waldeyer, or the neurone doctrine, has been somewhat modified since 

 Held, in 1896, noticed in some neurones an actual contiguity of the axones both with 

 the cell-bodies and dendrites. Held's observation was very soon confirmed by a num- 

 ber of investigators and was further extended to another group of neurones. Held's 

 observation, however, does not oppose the neurone doctrine, for he notices a mere con- 

 tiguity of the axones with the cell-body and dendrites and not an organic continua- 

 tion of one into the other. In the following year Bethe (1897) published an article 

 in which he claims that the nerve-cells and dendrites contain a great number of primi- 

 tive neuro-fibrils which run toward the axone and form the nerve-fiber. That is, the 

 nerve-fiber is composed of these primitive fibrils. He believes, further, that the fibrils 



186 



