SECTION OF CEIIEBRAL AND CEREBELLAR CORTEX. 69 



and at other times almost pointed ; often the edges of the 

 frond are " entire," but sometimes they are clothed with 

 dense tufts and fringes of " proliferous forked leaflets." 



The specimen with tetraspores first examined by E. M. 

 Holmes was from Mr. Isaac Carroll's collection, and was 

 doubtless gathered in Cork Harbour. The one from which 

 the figure on Plate xxxvii of Grevillea was drawn is stated 

 to have been gathered in Scotland. It would be intei-esting 

 to know from what part, as this will be the most northern 

 habitat as yet known. — Extract from Minutes of Dublin 

 Microscopical Club for November 18, 1875. 



Preparation of Sections q/* Cerebral and Cerebellar 

 Cortex /(??• Microscopic Examination. ByW. Bevan 

 Lewis. 



The histological analysis of animal tissues, so far as it 

 relates to processes of preparation and staining for the better 

 differentiation of the elementary constituents under micro- 

 scopic examination, has long been regarded as an important 

 item in physiological and pathological research. Much has 

 already been accomplished in this sphere of labour, yet much 

 still remains to be done, especially in the histology of the 

 central nervous system. New statements in regard to the 

 staining of brain sections which have recently been advanced 

 require mature consideration and experimental verification 

 before they become standard facts for the guidance of the 

 physiological inquirer. Until this sifting of evidence is 

 accomplished we cannot hope to find any substantial basis 

 for the establishment of histological science. 



The constituents of the cerebral cortex differ much inter se 

 in the facility with which they acquire the coloration neces- . 

 sary for a good delineation of their outline and structure. 

 Thus, while it is but a trivial task to stain equably and 

 deeply the smaller cells of the different layers of a con- 

 volution or the granular layer of the cerebellum, or even 

 to bring distinctly into view the nuclei of the blood- 

 vessels or the contour of the nerve-fibres, it is a far more 

 difficult matter to effect a good staining of the pyramidal 

 cells or the process of the cells of Purkinje. By 2igood stain- 

 ing I mean a deep staining, which yet leaves the cell con- 

 tents as unaltered as possible, the nucleus and nucleoli clearly 

 exposed to view, and the numerous minute extensions of 

 these bodies well defined. Undoubtedly a really good section 



