For March, 1921 



503 



If we maintain our definition of symbiosis to be a 

 partnership in which each derives some advantage from 

 the arrangement, then the association of plants and in- 

 sects, whereby the plant secures cross-pollination by pro- 

 viding the insects with nectar and pollen, must be set 

 down as another case of symbiosis. Associations of this 

 are often extremely close in some cases. In the yucca 

 the pollinating insect actually collects pollen, and packs 

 it down in the pollen chamber at the top of the pistil be- 

 fore laying her eggs in the young seed pod. Apparently 

 the yucca flowers can not be pollinated by any other in- 

 sect, and the insect cannot get along without young yucca 

 seeds for its larvse. The bees are remarkably adapted 

 to their work of serving the flowers, having capacious 

 pockets on their hind legs for carrying pollen and a crop 

 for transporting the nectar. Though working entirely 

 for themselves, they, nevertheless, benefit the plant. A 

 large number of bees seem adjusted to single kinds of 

 flowers, and are found on the wing only during the 

 blooming season of their favorite blossoms. Orchids are 

 often adjusted to the visits of a single species of insect, 

 and when for any reason this particular insect is absent 

 they set no seeds. 



Instances of ant and plant partnerships are conmion in 

 our gardens. The peony is frequented during the bloom- 

 mg season by large black ants intent on getting the nectar 

 so abundantly produced by the sepals. Since these ants 

 are notoriously pugnacious it is possible that they may 



protect the plants from other insects. The little partridge- 

 pea has tiny saucers on its petioles into which oozes nec- 

 tar from a small opening in the center that is equally 

 pleasing to ants. Some tropical species of legumes have 

 hollow thorns inhabited by multitudes of stinging ants 

 which swarm out to repel the invader whenever the plant 

 IS disturbed. It was once believed that the plants main- 

 tained the ants as a body-guard, producing little edible 

 bodies on the leaves for their use, but a well-known nat- 

 uralist has given it as his opinion that the ants are no 

 more necessary to the plants than fleas are to a dog. 

 Sotue of the tropical ferns also keep ants, or at least the 

 ants inhabit chambers in their rootstocks, and, in a meas- 

 ure, guard the plant. Species which harbor ants in this 

 way are called myrmecophilous plants. 



A familiar form of symbiosis is fotmd in such plants as 

 produce edible fruits. These fruits are designed to be 

 carried away by birds and other animals, and thus the 

 seeds are distributed. Both the plant and the animal, of 

 course, derive benefit from the transaction. But at this 

 point we begin to depart from instances of true symbiosis 

 and arrive at a stage where the association is not close 

 enough to be dignified by the name. Many such will 

 doubtless come to mind. Even man has found symbiosis 

 useful at times ; for instance, taking the horse to work for 

 his board, and providing the cow with daily food and 

 shelter in return for certain constant supplies of milk and 

 butter. 



March Birds 



PAUL B. RIIS 



The note of the first bluebird in tlie air answers to the 



purling rill of the melted snow beneath. 

 It is evidently soft and soothing and as surely as the 



thermometer indicates a higher temperature. 

 It is the accent of the south wind, its vernacular. — Thorcau. 



THE bluebird's note of pure gladness, that messenger 

 of Springtime, is carried to us on a balmy air. 

 How its sweet warble challenges the lingering 

 northwind, robbing it of its paralyzing sting I King Boreas 

 is grudgingly giving ground to the gentle awakening of 

 life's dormant impulses ; the balm of flooding sunlight 

 reaching deep into the shadowy depths of the forests. 

 Again we may live through Natttre's childhood and take 

 new delight in its simple gifts growing richer from day 

 to day. 



The bluebird, "shifting its light load of song from 

 post to post along the cheerless fence," greets our arrival 

 at the selfsaiue spring-brook, which daringly tempted our 

 mettle in January. The snow is lying in patches where 

 the protecting shadows of woodland and forest fall 

 densest. How barren and hopeless it seemed two months 

 ago. But what a subtle change has taken place. The 

 boisterous brook, unrestrained by the icy hand of Boreas, 

 is violently tumbling down its winding course. The king- 

 fisher, our old acquaintance, greets us with a vigorous 

 challenge of assurance, while a number of robins are 

 enjoying an early bath in the crystal waters with all the 

 abandon of Springtime. A little later we meet them 

 again in a friendly sumach thicket in company with the 

 bluebird partaking of a frugal meal, deftly plucking the 

 seeds from the velvety depth of sumach bobs. There 

 too in silent approbation, now at rest, now flitting from 

 limb to limb, we meet our avian friend Chesterfield, the 

 cedar waxwing, gathering the spare seeds of the hack- 

 berry. They are immaculately clad in gray and olive 

 and their red insignia completes the harmonious touch 



of correctness. Politeness forbids to take note of the 

 intruder and their pantomine suft'ers little from our at- 

 tention. 



Like the streams in Springtime, the stream of migra- 

 tion is gathering volume. Leisurely we observe a rough- 

 legged hawk patrolling the valley in spiral flight un- 

 hurried and confident, while the not tmiutisical note of 

 the bronzed grackle breaks the silence. The clear liquid 

 notes of the meadowlark from a distance proudly pro- 

 claim, "Spring of the Year, Spring of the Year." In 

 assurance we observe the massive trunks of the elms, 

 fed by perpetual fountains of springs. Rising like the 

 pillars of Hercules, their fibres are again surging with 

 the stream of life ; the swelling buds glistening in the 

 brilliant sunshine. 



The blue jay, noisily protesting our advance is join- 

 ing in the flock and presently we listen to its artful plead- 

 ing attempts to beguile a mate. The flocks of tree spar- 

 rows have grown abundant, "their erstwhile tinkling 

 notes, like sparkling frost crystals,'' now transformed 

 into a sweet canary-like warble. 



Slate colored juncoes are flitting across our path, their 

 twittering" trill mingled with the phe-be call of the 

 chickadee. And yet, in the abundance of early Springtime 

 we hear strains of surpassing beauty, a well modulated, 

 carefree warble, the song of the purple finch. The rich 

 outpouring of a yearning heart, incomparable and match- 

 less finds little rivalry among the songsters at anv tiiue. 

 .And later in the month, how one's heart bleeds for these 

 early arrivals, misled with the homing instinct strong 

 within. March in its proverbial madness is but fitfully 

 generous. The golden days of sunshine have yielded 

 to sleet and snow. Again the hills are windswept and 

 the meadows, valleys and woodlands become strangely 

 silenl. The carol of the robin, the endearing warble of 

 (Continued on page 512) 



