THE HISTOLOGY OF DISSEMINATED SCLEROSIS. 647 



In the changes in the optic nerve also, there were evidences of a primary change 

 both in the connective-tissue elements of the endoneurium and in the glia septa. 

 Similar changes are described by Fleming in retrobulbar neuritis in cases of intra- 

 cranial tumour, and are ascribed by him to a toxic condition of the cerebro-spinal 

 fluid. In other areas, especially where there was a gradual atrophy of the myelin 

 sheath, an indirect action of the sclerosis on the nerve fibres could be traced, 

 possibly by the sclerosis limiting the expansion of the blood-vessels, and inter- 

 fering with the nutrition of the nerve fibres, but it is far from this to the direct 

 compression causing destruction. 



In referring to the histological study it will be noted that I seem to be in 

 further agreement with the supporters of this view in looking upon the first change 

 as being evidenced in the glia tissue. There it has been stated that an enlarge- 

 ment of the protoplasm and protoplasmic processes of the normally existing spider 

 cells was the first change visible, but this must be referred rather to the difficulty 

 of recognising, by such staining methods, an early change in the nerve fibre, and 

 a change in isolated glia cells must be looked upon as being in the great majority 

 of cases simultaneous with or possibly later than that in the myelin sheath. It 

 has also been repeatedly stated in the histological study that the enlargement and 

 proliferation of the glia cells can be traced amongst the normal fibres at the margins 

 of the demyelinated tissue. This change and the presence of the nucleated peri- 

 pheral zone of glia cells seem to us to be not necessarily a proof of the primary 

 and essential change being related to the glia elements. Its possible significance 

 will be referred to later in relation to the varying factors which may influence the 

 development of the process, for it is important to recognise that the areas do not 

 always develop proportionately. 



A brief allusion may be made to the various functions attributed to the 

 neuroglia. It is no longer held that the glia cells and their processes conduct 

 the nutritive substance from the vessels to the nerve cells and fibres, and it is also 

 probable that the neuroglia must be looked upon as more than a supporting 

 structure or as a tissue element which serves to isolate the ramifications of the 

 neurones. Lugaro has put forward the interesting and suggestive view that the 

 glia serves to transform the products of metabolism of the nervous tissues and to 

 render them inoffensive — the peri-vascular glia thus acting as a filter. Nageotte 

 and Babes have both ascribed to the glia cells a secretory action in virtue of their 

 derivation from epithelial cells. 



2. Changes in the Nerve Elements — Nerve Fibres and Ganglion Cells. 

 Eedlich, Huber, Storch. and others have contended that the "noxa" acts 

 directly and primarily upon the nerve fibre before there is any trace of glia pro- 

 liferation or vessel alteration. This change may be purely degenerative or an 

 actual inflammatory degeneration. The interstitial changes in the glia may be, 



