26 



BOYS AND GIRLS IN BIOLOGY. 



forms a wall of itself. In the second place, the torula 

 can make its own food, or protein, out of the raw ma- 

 terial it finds in the liquid, while the animal-cells seem 

 to have no such power ; they must have their protein all 

 ready made, and their work is to destroy it. So if the 

 torula is not a mineral nor an animal, it must be a 

 vegetable. Vegetables are the manufacturers or pro- 

 ducers of protein ; animals are the destroyers or con- 

 sumers of it. This is why I asked you to remember 

 protein : plants can make it, animals cannot, and this 

 is one great difference between plants and animals or 

 between you and your spoonful of yeast. And so you 

 might call the vegetable kingdom Nature's big kitchen, 

 where the mineral kingdom is cooked and made ready 

 to be eaten by the animal kingdom. The vegetable- 

 cells with their white sacs are the little cooks in white 

 aprons ; how clean they are, and how fast they work ! 

 They are such intelligent little creatures, too, they 

 never burn up the dinner nor let it sod, for they know 

 just how to regulate the heat of their ovens. They 

 do not spoil your digestion with pastry or confections, 

 and they are so economical, that they never let a bit of 

 any thing go to waste. If we had such cooks in our 

 kitchens, we should never die of dyspepsia or poverty. 

 Some plants have been noticed standing outside the 

 kitchen-door, catching flies, stray bits of meat, or any 



