THE MAMMALIAN NERVOUS SYSTEM 61 



methylene-blue (1 part to 10,000 parts of water) and stain for 

 fifteen minutes. Rinse off the stain, add a drop of water, and 

 cover with a cover-slip. Examine with low and high powers 

 of the microscope and draw a typical neuron with its processes. 



(b) Now lay out all of the slides of fixed and permanently 

 mounted sections of the spinal cord supplied in the loan collec- 

 tion of microscopic material and examine them to get a general 

 view of its internal structure. Compare sections through the 

 spinal cord prepared by different histological methods (Weigert, 

 Nissl, Golgi, Cajal, etc.) and note which histological elements 

 are best revealed by each of the methods used. Draw on a large 

 scale typical neurones from the ventral gray column from several 

 of these preparations. Look up the technic employed in these 

 methods and the purposes for which each is best adapted. On 

 the study of pathological degenerations and the embryological 

 development of fiber tracts see Section 68 (b) and (c). A thor- 

 ough neurological study of any part requires the use of several 

 histological methods, since each of them is specific for some ele- 

 ments only of the tissue. 



(c) Literature on the neuron: Barker ('10), Chapters I to IV; 

 Herrick ('15), Chapter III; Meyer ('98); Sheldon ('18), Chap- 

 ters XVI to XX; Starr, Strong and Learning ('96). 



64. Make a composite drawing of one-half of a section of the 

 spinal cord from Weigert and Nissl (or toluidin blue), sections 

 to show the arrangement of both white matter and nerve-cells. 

 See Herrick ('15), Figs. 57, 58; Morris ('14), Fig. 616, pp. 778, 

 779; Villiger ('12), Figs. 94, 95, pp. 91, 92. Draw the outline 

 and the details of the white matter from a Weigert section and 

 the details of the gray matter from a Nissl section. Label 

 fully all parts, particularly the cell clusters ("nuclei"). Note 

 the relations of the non-nervous elements (ependyma, blood- 

 vessels, connective tissue), neurons, their cell bodies (perikarya) 

 and processes, and the myelinated nerve-fibers. In the gray 

 matter (substantia grisea) identify and designate the columns: 

 columna grisea ventralis (ventral horn), columna grisea lateralis 

 (lateral horn), columna grisea dorsalis (dorsal horn), the sub- 

 stantia gelatinosa of Rolando, the nucleus thoracalis in the tho- 

 racic region (nucleus dorsalis Clarkii of the B NA , posterior vesic- 

 ular column of Clarke, Clarke's Column), the reticular formation 



