MUSCLE TISSUE 129 



muscle no new element appears, the contractile fibrillcE representing nothing more 

 than a specialization of the already contractile spongioplasm. 



TECHNIC 



(i) Isolated Smooth Muscle Cells. — Place small pieces of the muscular coat 

 of the intestine in o.i-per-ccnt. aqueous solution of potassium bichromate, or in 

 30-per-cent. alcohol for forty-eight hours. Small bits of the tissue are teased 

 thoroughly and mounted in glycerin. Nuclei may be demonstrated by first 

 washing the tissue and then staining for twelve hours in alum carmine (p. 19). 

 This is poured off, the tissue again washed in water and preserved in eosin-glyc- 

 erin, which gives a pink color to the cytoplasm. 



(2) Potassium hydrate in 40-per-cent. aqueous solution is also recommended 

 as a dissociater of smooth muscle cells. Pieces of the muscular coat of the intes- 

 tine are placed in this solution for five minutes, then transferred to a saturated 

 aqueous solution of potassium acetate containing i-per-cent. hydric acetate for 

 ten minutes. Replace the acetate solution by water, shake thoroughly, allow 

 to settle, pour off water, and add alum-carmine solution (p. 19). After twelve 

 hours' staining, wash and transfer to eosin-glycerin. 



(3) Sections of Smooth Muscle. — Fix small pieces of intestine in formalin- 

 Miiller's (technic 6, p. 7) or in Zenker's fluid (technic 10, p. 8). Thin transverse 

 or longitudinal sections are stained with haematoxylin-eosin (technic i, p. 20), 

 and mounted in balsam. As the two muscular coats of the intestine run at right 

 angles to each other, both longitudinally and transversely cut muscle may be 

 studied in the same section. 



(4) Striated Voluntary Muscle Fibres.— One of the long muscles removed 

 from a recently killed animal is kept in a condition of forced extension while a i- 

 per-cent. aqueous solution of osmic acid is injected into its substance at various 

 points by means of a hypodermic syringe. Fixation is accomplished in from 

 three to five minutes. The parts browned by the osmic acid are then cut out 

 and placed in pure glycerin, in which they are teased and mounted. 



(5) Sections of Striated Voluntary Muscle.^Fix a portion of a tongue in 

 formalin-Miilier's fluid or in Zenker's fluid (p. 8). Thin sections are stained 

 with haematoxylin-picro-acid-fuchsin (technics, p. 21) and mounted in balsam. 

 As the muscle fibres of the tongue run in all directions, fibres cut transversely, 

 longitudinally, and obUquely may be studied in the same section. The sarco- 

 lemma, the pointed endings of the fibres, and the relation of the fibres to the con- 

 nective tissue can also be seen. 



(6) Isolated heart-muscle cells may be obtained in the same manner as smooth 

 muscle cells. (See technic i, above.) 



(7) Sections of Heart Muscle. — These are prepared according to technic 3 

 (above). By including the heart wall and a papillary muscle in the same section, 

 both longitudinally and transversely cut cells are secured. The stain may be 

 either haematoxyhn-eosin (technic i, p. 20), or haematoxylin-picro-acid-fuchsin 

 (technic 3, p. 21). 



