CONNECTIVE TISSUE, CARTILAGE, AND BONK. in:; 



ing the tissue for from one to six hours in 1 per cent, osmic 

 acid. From this it is transferred to 5 per cent, tannic acid, or 

 to a mixture of tannic and pyrogallic acids, and left for from 

 eighteen to twenty-four hours. This gives a very clear picture 

 of all protoplasmic structures. A counter-stain of safranin may 

 be used. A useful modification of this method can be employed 

 on sections (MacCallum). These are placed for one minute in 

 the osmic acid mixture, washed in water, and transferred for 

 two minutes to the reducing fluid. If this stain is not suffi- 

 ciently intense, the sections may be washed in water, and the 

 process repeated. 



3. CONNECTIVE TISSUE, CARTILAGE, AND BONE. 



10. For gelatinous connective tissue, the umbilical cord of a 

 three to four months human foetus, fixed in Zenker's fluid and 

 stained in hsematoxylin, may be employed. The subcutaneous 

 tissue of very young pig's embryos can also be studied. 



11. Areolar connective tissue may be obtained by producing 

 artificial oedema in the subcutaneous tissue or in the intermus- 

 cular septa. This is done by injecting physiological salt solu- 

 tion by means of a hypodermic syringe into the loose tissue 

 under the skin of a rabbit or rat. From the swollen tissue 

 thus produced a small piece is cut and spread out under a cover 

 glass. Various chemical tests may be made with such prep- 

 arations. Magenta, acid fuchsin, and methylene-blue give 

 good results in staining areolar tissue. 



12. White Fibrous Tissue. The tendons from the tail of 

 a rat, or from the ankle of a pig, are the most available source 

 from which to obtain this tissue. This may be studied fresh, 

 or after having been acted on for twenty-four hours by a satu- 

 rated solution of picric acid. In ordinary sections, white 

 fibrous tissue is colored red in Van Gieson's fluid (acid 

 fuchsin, picric acid), while elastic fibres are stained yellow 

 and muscle brown. 



13. Tendon Cells. A small piece of the tail of a rat is 

 placed in alum carmine solution for several days. It is then 

 teased out and examined in glycerin. 



