128 



MANUAL FOR SUGAR GROWERS. 



stance in the tin, leaving a small hole in the lid for 

 the escape of air. The tin and its contents are now 

 heated to the temperature of boiling water in order 

 to kill the putrefactive germs which are present, — 

 not merely to remove the air, as is sometimes 

 supposed, — and while hot the small hole is closed 

 by means of a drop of solder. Cane-juice treated 

 in the same manner would remain unchanged for 

 any length of time. Air free from germs will not 

 cause any fermentative or putrefactive change. 



If a drop of liquid in which sugar is undergoing 

 change from sugar to alcohol be examined under a 



microscope, a great number 

 of little bladder-like bodies 

 will be seen floating about in 

 it, the appearance when high- 

 ly magnified being as in the 

 figure. These are the germs 

 of alcoholic fermentation, or 

 the yeast-plants, as they are 

 called. Each little plant con- 

 sists of a single cell, and mul- 

 tiplies by budding. A pro- 

 jection forms on one side of the parent cell, and this 

 gradually grows until it becomes a perfect cell like 

 the parent. This is known as reproduction by gem- 

 mation or budding. The yeast-plant also multiplies^ 

 by forming spores in its interior. The contents col- 

 lect into masses which, on the rupture of the sur- 

 rounding cell-wall, are set free and develop into 

 new yeast-cells. This method of multiplying is less 

 common than the former. 



Fig. 19.— Yeast plant (highly 

 magnified). 



