10 



BOYS AND GIRLS IN BIOLOGY. 



of the large lecture-room, and what do you think was 

 on the table before him ? A cup of yeast — the very 

 thing I wanted to know about ! 



This was his subject, and, as he talked, it seemed to 

 me, somehow or other, he must have heard of our ex- 

 periment, else how could he tell just what to say % So 

 clearly did he explain how that old jar foamed over 

 every morning, I thought all you boys and girls would 

 like to hear about it, too ; so I shall try to tell you. I 

 am sure I should have been very glad if I had been told 

 something of the kind, instead of being scolded and 

 called a naughty child. 



Now, if you will get a little yeast to look at while 

 I talk, you will better understand what I say— just a 

 spoonful or two in a glass or cup will do. Let me tell 

 you that every thing you notice about this yeast has 

 a meaning. I cannot tell you about all the things you 

 may see ; but I can tell you about some of them, and, 

 when you get older, you can perform original experi- 

 ments and find out other things for yourselves. The 

 first thing that you will probably notice about the yeast 

 is, that it bubbles, and these bubbles look something 

 like the soap-bubbles with which you and I have so 

 often played ; but we have to make our soap-bubbles, 

 while these seem to make themselves. Soap-bubbles 

 come from the air which is caught in the water, and is 



