MUSCLE NERVE-ENDINGS • 443 



terminations of Vertebrates the best method is his lemon-juice 

 process (§ 405). 



See also the methods of Apathy, §§ 407, 410. 



944. Nerve-endings — the Silver Method. Ranvier employs it 

 as follows {ibid., p. 810) ; Portions of muscle (gastro-cnemius 

 of frog) having been very carefully teased out in fresh serum, 

 are treated for ten or twenty seconds with nitrate of silver solution 

 of 2 to 3 per 1000, and exposed to bright light (direct sunlight 

 is best) in distilled water. As soon as they have become black 

 or brown they are brought into 1 per cent, acetic acid, where 

 they remain until they have swollen up to their normal dimensions. 

 They are then examined in a mixture of equal parts of glycerin 

 and water. 



This process gives negative images, the muscular substance 

 being stained brown, and the nervous arborescence unstained. 

 The gold process gives positive images, the nervous structures 

 being stained dark violet. 



945. Nerve-endings — the Bichromate of Silver Method. The 

 rapid method of Golgi has been used by Ramon y Cajal for 

 the terminations of nerves and tracheae in the muscles of insects. 

 See Zeit. wiss. Mik., vii, 1890, p. 332, or fourth edition. A modi- 

 fication is used by Wunderer, Arch. mik. Anat., Ixxi, 1908, 

 p. 523. 



946. Muscle-spindles. See Cilimbaris, Arch. mik. Anat, Ixxv, 

 1910, p. 692. Principally intra-vitam methylen blue, by injection 

 through the internal carotid. For elastic fibres Weigert's resorcin- 

 fuchsin, followed by 1 per cent, orcein acidified with HCl. 



ELECTRIC ORGANS 



947. Electric Organs. Ranvier {Traite, Chap, xviii), finds 

 that osmic acid is the only reagent that will fix properly the 

 terminal arborisations on the lamella;. He injects a little 2 per 

 cent, solution under the surface of the organ, removes a small 

 portion of it after a few minutes, and puts it into a quantity 

 of the same solution for twenty-four hours. The electric plates 

 may then be teased out and examined in water, and will show 

 the stag's horn ramifications ; and the dissepiments between 

 the columns will show the bouquets of Wagner. The terminal 

 arborescence may be impregnated with silver. A portion of 

 the surface of the organ is rubbed with lunar caustic until it 

 appears opaque, then removed and the plates teased out in 

 water. This gives negative images. 



Or, electric plates, isolated by teasing after twenty-four hours 

 in osmic acid as above, and kept for some days in one-third 

 alcohol, are washed and placed on a slide with their ventral 

 surface uppermost. They are then treated with a few drops of 



