NO ONE perhaps ever lived who excelled Henry D. Thoreau as a general observer of nature. He patiently and with minute care examined both animate and inanimate creation, and wrote down an accurate account of his observations, noting particularly the effects produced by the changes in the seasons. He worked diligently to discover the first sign of spring, with results not wholly satisfactory. In one place he asks: "What is the earliest sign of spring? The motions of worms and insects? The flow of sap in trees and the swelling of buds? Do not the insects awake with the flow of the sap? Bluebirds, etc., probably do not come till the insects come out. Or are there earlier signs in the water, the tortoises, frogs, etc.?"

He found that whenever there was a warm spell during the winter some forms of vegetation, particularly the grasses and water plants, would begin to grow, and some would even bloom in favorable locations, as the skunk cabbage. He did not fully settle the question as to what would begin to grow first in the spring, whether it was the catkins of the swamp willow or the stems and leaves of the equisetum in the pool, or something else.

A list of the most striking phenomena observed by Thoreau in early spring is given below, and is extracted from his journals, written when he lived near Boston, during the years 1840 to 1860. In each case the earliest date mentioned by Thoreau is given, there being a difference of about a month between the earliest and latest spring. Many of these phenomena and the order in which they occur are common to a large extent of country, including the eastern and northern central states. Thus, the skunk cabbage is the first flower in all this region. A few notes are added, showing variations.

February 21—Sap of the red maple flowing. This was in 1857. It does not usually flow until the second week in March.

February 23—Yellow-spotted tortoise seen.

February 24—The bluebird, "angel of the spring," arrives; also the song-sparrow. The phebe or spring note of the chickadee, a winter bird, heard.

"The bluebird and song-sparrow sing immediately on their arrival, and hence deserve to enjoy some preËminence. They give expression to the joy which the season inspires, but the robin and blackbird only peep and tchuck at first, commonly, and the lark is silent and flitting. The bluebird at once fills the air with his sweet warbling, and the song-sparrow, from the top of a rail, pours forth his most joyous strain."

March 1—The catkins of the willow and aspen appear to have started to grow.

March 2—The caltha, or cowslip, found growing in water.

The skunk cabbage in bloom in warm, moist grounds.

March 5—The red maple and elm buds expanded.

The spring note of the nut-hatch heard: To-what, what, what, what, what, rapidly repeated, instead of the usual quah quah of this winter bird.

March 6—The gyrinus (water-bug) seen in the brook.

First blackbird seen.

Green sprouts of the sassafras, hazel, blueberry, and swamp-pink found.

March 7—Fuzzy gnats in the air.

First robins.

Spring note of the shrike heard, probably silent during the winter.

March 8—Willow buds expanded. Sap flowing in the white pine.

Flock of grackles seen.

Radical leaves of the golden-rods and asters in water, growing decidedly.

March 9—Ducks seen.

March 10—Poplar and willow catkins started; also equisetum (horse-tail), saxifrage, and probably other water plants. The butter-cup found growing.

Shimmering in the air noticed, caused by evaporation; water in the brooks, "clear, placid, and silvery," both phenomena of spring.

March 12—Poplar catkins in bloom.

First meadow-lark seen.

March 14—Wild geese seen.

Fox-colored sparrows seen.

March 15—Grass growing in water.

Wood, or croaking frog heard; "the earliest voice of the liquid pools."

March 16—The first phebe bird heard. Gulls and sheldrakes seen.

March 17—Grass green on south bank-sides.

The first flicker and red-wing seen; also a striped squirrel; also some kind of fly.

March 18—The skunk cabbage, in moist grounds, abundantly in bloom, attracting the first honey-bees, who, directed by a wonderful instinct, leave their homes and wing their way, perhaps for miles, to find this first flower. This seems all the more remarkable when it is considered that the honey-bee is an introduced, not a native insect.

March 19—The first shiners seen in the brook.

March 20—Pussy-willow catkins in full bloom.

"The tree-sparrow is perhaps the sweetest and most melodious warbler at present."

"The fishes are going up the brooks as they open."

March 21—The garden chickweed in bloom.

The ground-squirrel's first chirrup heard, a sure sign, according to some old worthies, of decided spring weather.

The hyla, or tree-frog, begins to peep.

"The woods are comparatively silent. Not yet the woodland birds, except (perhaps the woodpecker, so far as it migrates) only the orchard and river birds have arrived."

March 23—The white maple in bloom and the aspen nearly so; the alders are generally in full bloom. "The crimson-starred flowers of the hazel begin to peep out."

March 24—Shore-larks seen.

March 28—Buff-edged butterflies seen.

March 31—The small red butterfly seen.

April 5—Swallows appear, pewee heard, and snipe seen.

April 6—Cowslips nearly in bloom.

April 7—Gold-finches seen; also the purple finch.

April 8—Pine warbler seen.

The epigÆa (trailing arbutus) nearly in bloom. "The earliest peculiarly woodland, [2] herbaceous flowers are epigÆa, anemone, thalictrum (or meadow rue), and, by the first of May, the violet."

April 9—Cowslips [3] (not a woodland flower) in bloom, "the first conspicuous herbaceous flower, for that of the skunk cabbage is concealed in its spathe."