THE BLOOD AND THE LYMPH. 349 



indispensably requisite. The best mode of proceeding is to dry- 

 portions of the vessel stretched out upon paper, in which con- 

 dition sections may be made even of very small vessels, which 

 are to be again moistened with water, and if it be wished to 

 study the muscular structure, treated with acetic or nitric acid 

 of 20 per cent. (Weyrich), or else with caustic soda, by which 

 reagents the elastic tissue is also very beautifully displayed. 

 For the speedy, isolated demonstration of the epithelium, the 

 elastic inner membrane, and the muscular tunic, the larger 

 vessels at the base of the brain have appeared to me to be the 

 best adapted; the elastic membranes of the t. media are readily 

 isolated by maceration in strong acetic acid. Its muscular 

 fibres are always to be seen upon simple teasing out; or else 

 readily, upon the addition of nitric acid. For the study of the 

 capillaries, the brain, the retina, the Tadpole and embryos are 

 above all to be recommended ; for their development, the 

 Tadpole, the allantois of embryos, and the vascular capsule of 

 the lens. The blood should be examined, when it is possible, in 

 the serum itself, afterwards with the various reagents above 

 noticed ; and regard must be paid to the great tendency to 

 change possessed by its elements. I inject lymphatic glands 

 with carmine and size, or with sealing-wax and resin dissolved 

 in alcohol ; I also recommend sections of preparations hardened 

 in alcohol.] 



Literature. — J. C. Fr. Wolff, in the ' Memoirs of the Peters- 

 burg Academy/ for the years 1780 — 92; J. Reid, Art. * Heart/ 

 and B. Searle, ' Fibres of the Heart/ in ' Cyclop, of Anat./ 

 II ; Parchappe, • Du Coeur, de sa structure et de ses mouve- 

 ments/ Paris, 1844 ; C. Ludwig, ' Bau der Herzventrikel/ in 

 'Zeits. fur rat. Med./ Bd. VII, p. 189, and ' Ueber die Herz- 

 nerven der Frosche/ in Miiller's 'Archiv/ 1848, p. 139 ; 

 Luschka, 'Das Endocardium und die Endocarditis/ in Virchow's 

 'Archiv/ IV, p. 171; Remak, 'Ueber die Ganglien des Herzens/ 

 in Muller's 'Archiv/ 1844, p. 463, and 'Ueber den Bau des 

 Herzens/ ibid., 1850, p. 76; R. Lee, 'Memoir on the 

 ganglia and nerves of the heart/ London, 1851 [and 'On the 

 Nerves which supply the Muscular Structure of the Heart/ 

 'Proceed. Roy. Soc./ Nov. 17, 1853, vol. vi, No. 99, p. 337]; 

 Bidder 'Ueber die Nervencentra im Froschherzen/ in Miiller's 

 'Archiv/ 1852, p. 163; R. Wagner, ' Symp. Ganglien des 



