94 PRACTICAL HISTOLOGY. 



tioned in speaking of the connective tissue, it is, 

 however, difficult, if not impossible, at the same time 

 to bring distinctly into view the outlines of the cell- 

 spaces by the silver method, and the bodies of the 

 cells themselves by some other method of staining. 



Preparation 5. No doubt one of the best and 

 most generally useful methods of coloring cell pro- 

 toplasm is that known as the gold method. This is 

 applied to cartilage in the following way. Thin 

 sections are made from the articular end of a fresh 

 bone and are placed in a few drops of a solution of 

 chloride of gold (1 part in 200 of \vater). After 

 half an hour they are transferred to a beaker con- 

 taining a comparatively large amount of distilled 

 water which has previously been slightly acidulated 

 with acetic acid, just so as to be distinctly acid to 

 the taste. The beaker is then covered with a glass 

 plate and placed in a window in as warm a place as 

 possible, and where it will be exposed for some hours 

 a day to the full sunlight. Here the sections are 

 left for two days, after which time they should have 

 acquired a dark violet color, and are ready to mount 

 in glycerine. But before this is done they should 

 first be examined with a low power in a drop of 

 water to see whether there is any precipitated matter 

 upon the surfaces of the sections. If this is the case 

 it must be brushed away with a camel-hair pencil, 

 the sections being held with fine forceps during the 

 process. When finally mounted and examined with 

 a high power, the cartilage cells should retain pre- 

 cisely their natural form and appearance, except that 

 they are stained of a faint violet tinge, whilst the 

 matrix remains almost entirely colorless. In sections 

 taken from the edge of the curtilage, the ramified 

 transitional cells which occupy the corresponding 

 cell-spaces shown by the silver method will be ren- 

 dered apparent. 



The coloration by the gold and silver methods appears 

 in some way to depend on the occurrence of a deposition 



