

753 



by a vast number of thorny and knobbed processes, generally of short 

 extent; giving to the entire cellular body a very shaggy appearance, 

 comparable to a mass of coarse moss with a central more dense por- 

 tion, hence the name of mossy cell. 



Very similar cells are depicted by Retzius j ) from a preparation 

 of a 26 cm long human foetus, occurring with in the gray columns 

 of the cord ; also somewhat similar figures are given by Andriezen 2 ) 

 from the cortex of the brain, under the name of protoplasmic glia 

 cells. Some of these cells are of very large size, and stretch between 

 the nerve bodies and fibres, covering an immense territory. Nearly all 

 of them have one or two longer extensions, that eventually loose their 

 mossy appearance, and run as almost straight fibres through con- 

 siderable areas of the brain substance (fig. 1, no. 14). 



I was at first inclined to think that, this mossy appearance was 

 increased by a deposit of silver precipitate in coarse form, upon very 

 slight lateral projections from the main arms, but afterwards found 

 numerous equally shaggy bodies in sections entirely free from every 

 trace of deposit. 



All the different described forms of neuroglia cells, with the ex- 

 ception of those belonging to the embryonal types, are in close relation 

 with the blood-vessels of their vicinity, the connection being made 

 by the application of their globular endings to the hyaline sheath of 

 the vessel. 



The region examined is very interesting, not only from the great 

 variety of neuroglia cells that may be seen within a very limited area, 

 but from the fact that varieties of ependymal neuroglia cells, pre- 

 viously supposed to have entirely disappeared from the central nervous 

 system in the adult mammal, are found present in perfect condition in 

 the brain of a very high order of animal, and are not confined, as 

 has previously been supposed, to those of adult reptiles, amphibia, 

 and fishes. 



1) Biol. Unters. N. F. V, 1892. 



2) Brit. Med. Journ., Jan. 1894. 



