HISTOLOGICAL DEMONSTRATIONS. 141 



axial cylinder process connected with the centre of the 

 base of the pyramid. 



From without inwards the layers of the gray matter, as seen in very 

 good specimens, are : 



1. A thin layer, consisting almost entirely of neuroglia. 



2. A thin layer of minute closely placed nerve cells of irregular 

 shape, with branching processes. 



3. A layer three or four times the breadth of either I or 2, con- 

 taining the pyramidal cells, scattered throughout its whole thickness. 



4. A thin layer of closely set small granule-like corpuscles of 

 irregular shape. 



5. A layer twice as broad as the last, consisting of cells, for the 

 most part of fusiform shape. This layer gradually merges into the 

 central white matter of the convolution. 



Fine fasciculi of medullated fibres pass outwards in the gray matter. 

 Other fasciculi of medullated (Meynert] fibres run at right angles to 

 these, and leave interstices that are occupied by the nerve cells and the 

 reticulum formed by their branching processes (Gerlach). 



b. Examine a V. S. cerebral convolutions injected, and 

 observe the greater vascularity of the gray as compared with 

 the white matter. 



GENERATIVE ORGANS. 



MALE ORGANS. 



249. Testis. Methods. Mihalkovics (Ludwig's Arbei- 

 ten, 1874, p. 19) recommends the following method of 

 hardening the testis for the purpose of section, as preferable 

 to all others : Inject, with a sharp-pointed syringe, i 

 per cent osmic acid at several points through the tunica 

 albuginea of the testis of a cat ; place it in rectified spirit 

 for several days, and then in absolute alcohol for a day or 

 two, previous to making sections. Stain with carmine or 

 logwood, and mount in glycerine. 



b. Hardening in Miiller's fluid, and then in alcohol, is 

 also a fairly good method for studying the cells in the 

 tubuli seminiferi in teased preparations. 



c. For the isolation of the tubules, Sappey long ago recommended 

 the maceration of small portions of the organ in dilute hydrochloric 

 acid (acid I, water 2 parts) for one or two days. 



