THE BLOOD AND THE LYMPH. 723 



The investigation of the heart, as regards the muscular fibres them- 

 selves, is easy, and their anastomoses will be found without difficulty in 

 every carefully made preparation. But great difficulties attend the 

 tracing of the course of the fibres in that organ. Hearts that have 

 been macerated in weak spirit are best adapted to this purpose ; the 

 boiling in water, also, of the recent heart, or of hearts that have been 

 previously in salt for some weeks, has been long recommended, a method, 

 instead of which Purkinje and Palicki advise the boiling in a solution of 

 common salt, or still better of sulphide of lime ; whilst Ludwig, after 

 removing the pericardium, lays the heart in water, and repeats this 

 maceration each time after the removal of a layer of the muscular sub- 

 stance, using at the same time slight pressure. For the bloodvessels, 

 the tearing of them into lamellae with the forceps and scalpel, which 

 alone was formerly employed, is not sufficient ; the examination of 

 transverse and longitudinal sections of the entire wall, being, in addition, 

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

 of the vessel stretched out upon paper, in which condition 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 dis- 

 played. 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, after- 

 wards 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 hard- 

 ened in alcohol. 



Literature. J. C. Fr. Wolff, in the " Memoirs of the Petersburg 

 Academy," for the years 1780-92; J. Reid, Art. "Heart," and B. 

 Searle, " Fibres of the Heart," in "Cyclop, of Anat.," II.; Par- 



we may add that the same subject has recently afforded, in blood taken from the finger one 

 or two hours after breakfast, a very considerable proportion of such corpuscles with red 

 "nuclei," affording every transitional stage between the ordinary colorless corpuscle and 

 the free red cellaeform nucleus. For these observations, however, water and very dilute 

 acetic acid were added to the blood. TRS.] 



