7o 



Attached to this important discovery are names of mark 

 in histology, as, besides that of M. INIax Schultze, we must 

 mention MM. Frommann, Babouchine, Arndt, Schwalbe, and 

 others. This structure, moreover, is not at all restricted to 

 the nervous fibres only, but extends, besides, to the ganglion- 

 cells. 



The form of ganglion-cells had not been sufficiently studied 

 till the present time. In the cerebral cortical substance 

 MM. Meynert, Arndt, Koschennikoff, and others, find that 

 the ganglionary cells have constantly a pyramidal shape. 

 The base of the pyramids is always directed towards the 

 centre, the summit towards the circumference. From this 

 summit proceeds a prolongation larger than all the others, but 

 of what sort histologists are not agreed. 



Researches on the histologic development of the nervous 

 system will be able, perhaps, to throw light on the nature of 

 the constituent elements of this system. Histologists are far 

 from being agreed on the nature of the granular framework 

 of the central nervous system — a framework to which different 

 names have been given, such as " reticulum,^^ ^' neuroglia,^^ 

 " glia,^' &c. Some regard it as a nervous substance, others 

 as a variety of connective tissue. ]VI. Besser ('Archiv fiir 

 Patholog. Anat.,' xxxvi, p. 307) was the first to endeavour to 

 sift the question by the study of the nervous cerebral ele- 

 ments in the newly born infant. He found that at the 

 moment of birth the development of the neuroglia is enor- 

 mous, and that this tissue, composed of nuclei and of a net- 

 work of granular fibrils, becomes by this transformation the 

 grafting stock, as it were, of all the elements found in the 

 brain later on. The differentiation of the nervous elements 

 is preceded, above all, by the formation of capillary vessels 

 on a large scale. The nuclei of the nervous cellules are the 

 result of a transformation of the nuclei of the neuroglia; 

 the substance itself of the cells results from a transformation 

 of the fibrillar network of this same neuroglia, which is also 

 the origin of the axial cylinders of the nervous fibres. Such 

 a method of formation leaves no place for a membrana 

 propria of nerve-cells. Besides, the greater part of modern 

 histologists do not hesitate to proscribe it. This method of 

 generation accounts for the fibrillar structure that so many 

 authors, especially since the works of Frommann and of 

 Beale, have recognised in the ganglion- ceils of the most diverse 

 regions of the nervous system. This structure is far from 

 being the result of a coagulation produced by the reagents 

 employed, as it is easier to recognise in fresh preparations 

 than in those which have become hardened bv the diftereut 



