Such are some of the solutions to the problem of life in winter which the plants and animals about us have worked out; such some of the forms which they undergo; the places which they inhabit.

To the thinking mind a knowledge of these solutions but begets other and greater problems, such as how can a living thing be frozen solid for weeks and yet retain vitality enough to fully recover?  How can a warm-blooded animal sleep for months without partaking of food or drink?  And greater than either, what is that which we call life?

I hold in my hand two objects, similar in size, color, organs, everything—­twins from the same mother in all outward respects.  One pulsates and throbs with that which we call “life.”  It possesses heat, bodily motion, animal power.  The other is cold, motionless, pulseless, throbless—­a thing of clay.  What is that “life” which the one possesses and the other lacks?  Ah, there’s the rub!  With the wisest of men we can only answer, “Quien sabe?” (Who knows?)

[Illustration:  WINTER HOUSE OF MUSKRAT.]

BIRDS’ NESTS

(FROM WAKE ROBIN.)[3]

BY JOHN BURROUGHS.

[3] Copyright by Houghton, Mifflin & Co.

[Illustration]

How alert and vigilant the birds are, even when absorbed in building their nests!  In an open space in the woods, I see a pair of cedar-birds collecting moss from the top of a dead tree.  Following the direction in which they fly, I soon discover the nest placed in the fork of a small soft-maple, which stands amid a thick growth of wild-cherry trees and young beeches.  Carefully concealing myself beneath it, without any fear that the workmen will hit me with a chip or let fall a tool, I await the return of the busy pair.  Presently I hear the well-known note, and the female sweeps down and settles unsuspectingly into the half-finished structure.  Hardly have her wings rested, before her eye has penetrated my screen, and with a hurried movement of alarm, she darts away.  In a moment, the male, with a tuft of wool in his beak (for there is a sheep pasture near), joins her, and the two reconnoitre the premises from the surrounding bushes.  With their beaks still loaded, they move around with a frightened look, and refuse to approach the nest till I have moved off and lain down behind a log.  Then one of them ventures to alight upon the nest, but, still suspecting all is not right, quickly darts away again.  Then they both together come, and after much peeping and spying about, and apparently much anxious consultation, cautiously proceed to work.  In less than half an hour, it would seem that wool enough has been brought to supply the whole family, real and prospective, with socks, if needles and fingers could be found fine enough to knit it up.  In less than a week, the female has begun to deposit her eggs,—­four of them in as many days,—­white tinged with purple, with black spots on the larger end.  After two weeks of incubation, the young are out.