Shinkishi Hatai 9 



this refractive limiting line is not demonstrable in the adult and comes to the con- 

 clusion that during the processes of growth the protoplasm of the related neurones 

 fuses. 



As is stated by Held, the cells in this locality are very favorable for the study of 

 the termination of the axones. As Fig. 6 (Plate XIV) shows, the terminals of an axone 

 come in contact with the cell-body along a groove or an elongated depression. This 

 groove on the cell-surface may coincide with the refractive area of Held. In most cases 

 more than one axone terminates on a single cell-body. Fig. 6 was drawn from the 

 material taken from a young white rat having a body- weight of 4.5 grams. In this 

 stage a number of axones terminate on each cell-body. No special area for the termi- 

 nation of the axones appears, since they are found in all regions of the cell-body, some- 

 times at the center and sometimes at the end of it. In all cases the terminals of the 

 branches present mere contiguity to the cell-surface, and neither fusion of one with the 

 other nor a pericellular network of the axones is found. It is to be noted that these 

 observations apply to the white rat, while the observations of Held were made on the 

 rabbit. Whether the cell-body in the rat becomes fused with the axones in adult life 

 has still to be determined. 



A relation between axone and cell-body similar to that in the corpus trapezoideum 

 can be observed in the ventral horn cells of the spinal cord. Fig. 2 (Plate XIII), 

 which was drawn from the preparation of an adult white rat, illustrates this. In this 

 figure the cell-body is represented by sepia while the axone endings are colored an 

 intense red. 



2. Termination of the axone on the dendrites. — As has already been mentioned, 

 the gemmules are lateral extensions of the dendrites, and their essential structure is 

 the same as that of the dendrites. A careful observation of the preparation shows that 

 the axones in most cases surround the dendritic branches and approach so closely to the 

 gemmules that these two structures often come into contact. As Fig. 4 (Plate XIII) 

 shows, the cell-bodies in the Ammon's horn are densely surrounded by the axones and 

 some of the latter climb along the surface of the dendrites and there come into contact 

 with the gemmules. This relation is even more clearly shown in the cerebellar cortex. 

 It is already known that the dendrites of the Purkinji cells are densely surrounded 

 by several kinds of the axones ; namely, those of the granular cells, those form- 

 ing the climbing fibers, and those which form the moss-fibers. The axone termi- 

 nals which surround the dendrites come, in most cases, actually in contact with 

 the latter. Fig. 5 (Plate XIV) shows such a relation between the two processes 

 where the dendrites are represented in sepia, while the axones are colored an 

 intense red. 



The so-calle'd "glomeruli " formed by the axones and dendrites form the most favor- 

 able structure for the study of an intimate relation between the two processes. This 

 structure is found best developed in the olfactory-bulb and less developed in the granu- 

 lar layer of the cerebellar cortex. The olfactory glomeruli in Fig. 3 (Plate XIII) were 



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