624 



GROWTH OF HIGHER PLANTS 



the best results from the use of mercuric chloride. After the vacuum 

 apparatus is once assembled, the method is easy to manipulate and 

 gives a high percentage of viable seeds free of bacteria. The original 

 design of this apparatus as given by Hutchinson and Miller^ has been 

 modified. Fig. 1 shows the apparatus ready for use. Heavy walled 

 bottles (1 pint milk) and heavy steam-proof rubber tubing are very 

 convenient. 



The preparation of the apparatus for seed sterilization is a simple 

 matter. Bottle A serves to prevent air contamination. The large 

 tube which enters A is packed with non-absorbent cotton and the 



Fig. 1. An apparatus for the sterilization of seeds. 



exit tube of D with glass-wool; in the latter the plug prevents the seed 

 from escaping into E. The distilled water and the 0.25 per cent mer- 

 curic chloride solution are warmed. When the solutions are about 

 70-80°C., the mercuric chloride is poured into B, the water into C. 

 The warm solutions prevent the bottles from cracking when sterilized. 

 All rubber stoppers are then fitted tightly into the bottles and the 

 clamps, except 3, are closed. 



The entire apparatus is sterilized in the autoclave for 30 minutes 

 at 15 pounds pressure. When cooled to 40°C. the exit tube of E is 



2 Hutchinson, H. B., and Miller, N. H. J., /. Agric. Sc, 1908, iii, 185. 



