NERVE-ENDINGS. 351 



665. Nerve -endings. For the study of nerve-endings in 

 muscle, both motor and sensory, the four chief methods are 

 the methylen-blue method, the gold method, the silver method, 

 and the bichromate of silver method of Golgi. 



666. Nerve-endings the Methylen-blue Method. The prin- 

 ciples of the impregnation of nerve-tissue with methylen blue 

 have been explained in Chap. IX. 



BIEDERMANN'S procedure for the muscles of Astacus has been 

 indicated in 117 (see also Zeit. f. wiss. Mik., vi, 1, 1889, p. 

 65). After impregnating as there directed the carapace 

 should be opened, and the muscles exposed to the air in a 

 roomy moist chamber for from two to six hours, in order that 

 the stain may differentiate. The abdominal and caudal 

 muscles are those which give the best results. 



For Hydrophilus piceus } Biedermann proceeded by injecting 

 0*5 c.c. of methylen-blue solution between the ultimate and 

 penultimate abdominal rings, in the ventral furrow, and keep- 

 ing the animals alive in water for three to four hours. After 

 this time the thorax should be opened by two lateral incisions, 

 and the muscles of the first pair of legs (which are the most 

 suitable) removed and exposed to the air for three or four 

 hours in a moist chamber, and finally examined in salt 

 solution. 



GERLACH (Sitzb. k. math.-phys. Cl. k. layer. Akad. Wiss. 

 Miinchen, 1889, ii, p. 125; Zeit. f. wiss. Mik., vii, 2, 1890, p. 

 220) injected frogs, either through the abdominal vein or 

 through the aorta, with 4 to 5 c.c. of a 1 : 400 solution in 1 

 per cent, salt solution, and examined pieces of muscle (pre- 

 ferably the head and eye muscles) in serum of the animal, 

 afterwards fixing the preparations with picrate of ammonia 

 and mounting in glycerin jelly. 



The procedure of DOGIEL has been given in 117. 



667. Nerve-endings the Gold Method. FISCHER (Arch. f. 

 mik. Anat., 1876, p. 365) used the gold method proposed by 

 LOWIT ( Wien. Sitzgsber., Bd. Ixxi, Abth. 3, 1875, p. 1), and 

 employed by himself in his researches on the tactile cor- 

 puscles (Arch. f. mik. Anat., xii, p. 366) . See ante, 224. 



BIEDERMANN, in the paper quoted in the last section, recom- 

 mends for Astacus a similar procedure, the preliminary treat- 



