410 SPECIAL MICROSCOPIC TECHS IQ UK. 



(a) Physiological self-injection of Chrzonszczewski consists 

 in injecting the external jugular vein with a saturated aqueous 

 solution of indigo-carmine. It is injected three times in one 

 and one-half hours ; 25-50 cc. for a dog, 20-30 cc. for a cat, 

 and 15-20 cc. for a rabbit. At the end of this time the animal 

 is killed, and small pieces of the liver are hardened in absolute 

 alcohol. In frogs it is possible to place a piece of indigo- 

 carmine the size of a pea in the large dorsal lymph sac. 

 After twenty-four hours the animal is killed and the liver 

 examined. 



(b) Bile capillaries are demonstrated also by means of the 

 chrom-silver methods of Golgi (58). Small pieces of fresh 

 liver are placed for three days in osmium bichromate mixture 

 and then transferred to 0.75 per cent, aqueous silver nitrate 

 solution and left for from two to three days. After being 

 washed for a short time in water the tissue is hardened in 

 alcohol and cut into thick sections. 



9. ORGANS OF RESPIRATION. 



46. In order to demonstrate the respiratory epithelium, a 

 young cat is killed by decapitation and the lungs filled through 

 the trachea with a 0.05 per cent, silver nitrate solution. The 

 trachea is then tied off and the whole organ immersed in a 0.5 

 per cent, silver nitrate solution and left in the dark. After an 

 hour the lung is cut into pieces, which are hardened in the 

 dark in alcohol of increasing strength. The reduction may be 

 accomplished by exposing the pieces as a whole to sunlight or 

 by cutting sections and exposing them. 



47. Elastic tissue in the lung may be demonstrated by the 

 orcein stain or by Mallory's method. By maceration in 35 per 

 cent, potassium hydroxide solution the fibres can be isolated. 

 Beautiful specimens showing the framework of the lung can be 

 obtained by macerating pieces of lung in ^ per cent, potassium 

 bichromate for from one to three days. 



10. URINARY AND REPRODUCTIVE SYSTEMS. 



48. Kidney tubules may be isolated by treatment with HC1 

 for from ten to twelve hours. 



