252 



AGRICULTURE ON THE PACIFIC SLOPE 



the bottom of the pail, and allow the water to boil for 

 half an hour. Then to each pint of the mixture of 



gelatin and water add about 

 twenty drops of strained honey 

 or glucose or a lump of grape 

 sugar as large as a pea (mo- 

 lasses may contain substances 

 which prevent the growth of 

 bacteria). 



Add enough ammonia water, 

 or very weak lye, to make a 

 piece of red litmus paper turn 

 blue when a drop is placed on 



h b:,e P s a a* r p, e affo g n it. Be very careful not to put 

 the inverted pan in the bot- j n mO re of the lye or ammonia 



torn. (Sectional view.) 



water than is needed barely 



to turn the litmus paper blue. Now pour a little of 

 it into each of the dozen tumblers and cover with 

 cotton, as shown in figure 150. It is very much better 

 to use small 

 druggist's 

 vials as shown 

 in figure 151. 

 Also pour a 





FIG. 



153. Flat bottle containing gelatin, used for 

 counting bacteria. 



little gelatin 



into each of 



two flat bottles such as shown in figure 153, and leave 



them lying as shown in the figure, so that the gelatin 



