152 METHODS IN PLANT HISTOLOGY 



used basic fuchsin, prepared as follows: 50 mg. basic fuchsin is dis- 

 solved in 2 c.c. of 95 per cent alcohol and diluted with 100 c.c. of tap 

 water. Dr. Gourley used two lots of basic fuchsin, one from the Will 

 Corporation and the other from Coleman and Bell. Neither lot has 

 been certified by the Commission on the Standardization of Biological 

 Stains. Young or old plants of Coleus — tomato, bean, etc. — are lifted 

 from the soil and the roots are washed free of adhering material. The 

 root system is then immersed in the stain and a part cut off beneath 

 the surface of the solution. In 24-48 hours the bundles will be well 

 stained. Gourley succeeded with plants 6 feet in height. 



Cut off the upper 6 inches of a Coleus plant, immerse the lower end 

 in the stain and cut off 5 mm. of the stem under the surface of the stain. 

 In 24 hours, rinse off any surface stain in water. Transfer to 50, 60, 

 70, 85, 95, and 100 per cent alcohol, at least 12 hours in each. Better 

 change only once a day, especially with large pieces. Clear in f abso- 

 lute alcohol and \ xylol, ^ xylol and | alcohol, j alcohol and f xylol, and 

 pure xylol, 24 hours in each. The material is now ready for study but, 

 since xylol evaporates so rapidly, add cedar oil or carbon disulphide. 

 In a glass dish with a smooth bottom and an electric bulb underneath, 

 the vascular system can be traced in great detail. 



An ovule of a cycad, cut from the sporophyll under the staining solu- 

 tion, will have the vascular system well stained within 24 hours. 

 When dehydrated and cleared, the simple outer, and much-branched 

 inner, vascular supply are very striking. 



Small fruits and other objects can be studied in this way. In bottles 

 with wide mouth and glass corks, such preparations should keep for 

 years. 



After the stain has been taken up, material may be boiled in water 

 or in a very dilute solution of potassium hydrate. After partial disinte- 

 gration, pieces can be dissected so that the larger vascular units are 

 easily followed. 



Gourley's method is at its best where transpiration is strong and 

 the vascular system simple. 



STAINING LIVING STRUCTURES 



Some stains will stain living structures. Cyanin, methyl blue, and 

 Bismarck brown have been recommended for this purpose. The solu- 

 tions should be very dilute, not stronger than 1 : 10,000 or 1 : 500,000. 

 The solutions should be very slightly alkaline, never acid. It is claimed 



