CHAPTER XXXV. 



NEUKOGLIA AND SENSE ORGANS, 



Neuroglia.* 



909. Introduction. Neuroglia cells may be isolated by teasing 

 after maceration in weak solutions of potassium bichromate or 

 33 per cent, alcohol, and then stained, preferably by means of dilute 

 picrocarmine or other carmine solutions. They may be studied, 

 also, in sections made from non-embedded material fixed in solutions 

 of chromic salts and stained with carmine, nigrosin, orcein and so 

 on. Sections made from either fresh material hardened by the ether 

 freezing method and treated with a weak solution of osmic acid 

 ( 807), or from tissues hardened in potassium bichromate, can be 

 advantageously stained with watery solutions of anilin-blue-black 

 or nigrosin. Also, sections cut from material fixed, hardened and 

 embedded by the usual methods may, up to a point, be employed 

 for getting a general, though incomplete, view of the amount and 

 arrangement of the neuroglia in a given nervous organ. Iron 

 hsematoxylin, particularly after fixation in corrosive sublimate or 

 other fluids containing it, gives good results with sections of central 

 nervous organs of lower vertebrates, chiefly of fishes. 



See GOLGI, Opera Omnia, i, pp. 1 and 3 to 70 ; ii, p. 61 ; KANVIER, 

 Traite, etc. ; BEVAN LEWIS, op. cit. ; E. MULLER, Arch. mikr. Anat., 

 Iv, 1900, p. 17 ; STUDNICKA, Anat. Hefte, xv, 1900, p. 316, and the 

 literature quoted therein. 



But the best method for the study of the morphology and relation- 

 ship of ependyma cells and astrocytes has been for many years, 

 and in a sense still is, Golgi's rapid process ( 882), the best 

 material being that which has been placed for about two or three 

 days in the osmio-bichromic mixture. 



This method, however, does not allow of any tinctorial differentia- 

 tion, either between neuroglia cells and nerve cells, or between 

 neuroglia cells and neuroglia fibres. One might even say that it 

 is unsuitable for the demonstration of the latter, the existence of 

 which was clearly established only after the publication of 



* Rewritten by Dr. C. Da Fano, King's College, University of London. 



