Introductory 7 



though their crops are scanty. As we have said before, 

 the laborers on the great farm do not allow any surface to 

 be bare, if they can help it, and they work as if it were 

 their one object to grow as many crops as possible. The 

 very snow-fields and ice-fields are not allowed to lie idle, 

 for there is soil even here, and it must not be wasted. 



Dust, meteoric dust from the higher regions beyond 

 our atmosphere, is constantly falling all over the earth, 

 to the amount, it is believed, of more than five hundred 

 thousand tons every year; and though being scattered 

 evenly over the whole surface, it must be spread very thin 

 indeed; still, where there is no other mineral matter, as 

 on the snow and ice fields of the Arctic regions, it is quite 

 perceptible, and it is enough for the growth of such 

 humble vegetables as the "Red Snow," which in summer 

 covers the white surface with a flush of rose color many 

 miles in extent. Nor are this and other similar minute 

 plants grown to no purpose. These ''barren fields" are 

 also part of the great world's farm, an outlying part, it is 

 true, where the produce is not large; but such as they 

 are, the crops are needed, for there are glacier-fleas and 

 other live-stock even here, and these tiny vegetables sup- 

 ply them with food. 



Nature's laborers are such zealous and thrifty husband- 

 men that they are always on the watch to occupy every 

 inch of space where anything can be grown the moment 

 it is vacated, and even before. They will overrun our 

 gravel paths, and grow grass in our streets if allowed, 

 and they will take but a very short time to convert the 

 most highly cultivated garden into a wilderness without 

 any trace of a path in it, if it be given up to them. This 

 is true even in such temperate climates as our own, but in 



