THE FUNGUS, OR COLORLESS PLANT. H 



trying to get away, while the yeast-bubbles are formed 

 by a gas called carbonic acid, which is made by the 

 yeast. It was found by the bursting of these bubbles 

 that they did not contain common air like the soap- 

 bubbles, so men began to study yeast to find out what it 

 was that made all this blubbering, and I am going to 

 tell you all they have discovered so far. If you ask me 

 why the air does not stay in the soap-suds and the gas 

 in the yeast, I can tell you only that all kinds of gas, 

 and air, which is made of two kinds of gas, never will 

 stay in any one place unless they are held by strong 

 walls. I have seen you boys and girls sorry when you 

 could not make your toy-balloons stand out again and 

 go to the top of the room, now you know the reason 

 why ; the mischievous air inside had found a little hole 

 in the wall of the balloon, and the air outside helped 

 its imprisoned brother to escape through this hole. 

 Now, you are such little Yankees, you will be sure to 

 ask me if this air and gas are so restless, and try so 

 hard to get away from every place, why they do not 

 fly from the earth altogether, and leave us without any 

 thing to breathe, to burn, or to bubble. There is no 

 wall outside the earth to keep them from going, no ; 

 but there is a queer something called "attraction" 







that makes things fall down instead of up. Somebody 

 found it out one day when he was sitting under an 



