32 



THE AMERICAN MONTHLY 



[February, 



consists in dropping in the silver so- 

 lution, the elemental cells and their 

 proliferations are brought out as 

 finely granulated masses. On stain- 

 ing the dead cornea the vessels stand 

 out from a basement membrane dif- 

 fusely colored brown. 



167. Hoyer Beitriige zur anatomis- 



chen u. histologischen , Tech- 

 nik. Arch. mikr. Anat., xiii, 

 649-650. 

 Hoyer adds to a solution of silver 

 nitrate caustic ammonia, till the pre- 

 cipitate begins to dissolve. The mix- 

 ture is then diluted to 0.75-0.5% of 

 silver salt. This does not stain sur- 

 rounding tissue, only endothelium, 

 which show therefore more plainly. 



168. Hoggan, Geo. et Frs. Elizabeth. 



Etude sur les lymph atiques de 

 la peau. Journ. de I'Anat. et 

 Phys., 1879, XV, p. 54. 

 Etudes sur les lymphatiques des 

 muscles stries, 1. c. p. 588. 



For examinations of the skin these 

 authors combine salts of silver and 

 gold. They recommend a simple 

 apparatus. The piece of skin is 

 stretched over a rubber ring and a 

 second ring sprung on it. The cuti- 

 cle is uppermost when the little dish 

 thus formed is held so as to receive a 

 ^% solution of silver nitrate ; that is 

 allowed to remain for 30 seconds, 

 and then is substituted by a solution 

 of gold chloride of the same strength. 

 The muscular sheaths are treated the 

 same way, only the silver solution is 

 tsvice as strong. After acting for a 

 few seconds the preparation is ex- 

 posed for ten minutes to the light, 

 then treated a minute with the -J/o so- 

 lution of gold chloride and mounted 

 in glycerin. 



169. Hertwig, R. Ueber den Bau 



Ctenophoren. Jen. Zeitschr. 



f. Nat., xiv, 313 and 324. 

 Marine animals are so rich in 

 chlorides as to stain by silver nitrate 

 with difficulty, hence it is better to 

 harden them in dilute perosmic acid, 

 then wash in distilled water till only 

 slight precipitation occurs with silver 



nitrate, in which (1%) they are put 

 for about six minutes. 



170. Golgi. Sulla struttura delle fi- 



bre nervose midolate perifer- 

 iche e centrali. Arch, per le 

 sc. med. 1880, iv, 231. 

 Nerve fibres are treated with 

 chrome salts, osmic acid, and silver 

 solution. The fresh nei"vx of a rab- 

 bit is put for an hour in a mixture of 

 ten parts of potassivun bichromate 

 (2% sol.) and two parts of a 1% so- 

 lution of perosmic acid. The nerve 

 is then cut in pieces |^ to i cm. long 

 and put back in the mixture, and af- 

 ter some hours it is changed to a 

 0.5% solution of silver nitrate, in 

 which it remains for 8 hours. 

 Mounts may be in dammar. Bi- 

 chromate of potash is used alone for 

 from four hours to 15 days, accord- 

 ing to the kind of nerves, which are 

 then treated in the dark for 12-24 

 hours with silver nitrate, and mounted 

 in dammar before exposure to light. 



171. Sattler. Die Verwendung des 



Lapisstiftes zur untorsuchung 

 der Epithelien. Arch. mikr. 

 Anat., xxi, 672-677. 

 A pencil of caustic silver is rubbed 

 over the surface to be examined, and 

 it is then placed in water acid- 

 ulated with acetic or formic acid, ex- 

 posed to the light for a few minutes, 

 and mounted in glycerin. 



From the microscopical text-books 

 Gierke extracts : — 



172. Ranvier. Technisches Lehr- 



buch des Histologic, 1877. 

 The material, if membraneous, is 

 to be stretched on a flat surface, 

 washed with water from a pipette 

 allowed to flow over it, followed im- 

 mediately by the silver solution, and 

 again washed with water. Sections 

 are treated in a similar manner. If 

 the silver solution is too weak, as 

 1-500 or i-iooo, or the light too fee- 

 ble, there is a uniform coloration 

 quite different froin impregnation 

 proper, in which the nucleus should 

 be darkest, the protoplasma lighter, 

 and the intercellular substance least 

 colored of all. 



