88 THE POPULAR SCIENCE MONTHLY. 



drops its two sepals as they open, leaving the delicate, pure, white 

 petals and the April insects to succeed as best they can in the work of 

 cross-fertilization. Just what kinds of bees, or bugs, or beetles stand 

 ready to rob each opening flower of its sticky pollen, I am not prepared 

 to say. It is true that the blood-root has few competitors, at this time 

 of year, for the employment of the insect tribes. Its petals are large, 

 and doubtless catch the watchful eyes of the hungry insects at long 

 range. The plant and the insect work together, each selfishly, yet 

 each successfully. The mutual adaptation existing between some flow- 

 ers, as those of many orchids and their attendant insects, is so complete 

 that neither the plants nor the insects could well exist without one 

 another. Some plants are absolutely dependent upon certain insects for 

 the transfer of their pollen, while these same insects could not subsist 

 without the flowers from which to extract their daily food. In our 

 little blood-root, we do not believe such a thorough dependence exists* 

 If insects do not bring more potent pollen from some other flower, that 

 of its own, falling upon the stigma close by, will suffice. 



On April 13th two species were found in flower, and between them 

 there are seemingly wider differences of structure than were pointed 

 out in the last two. The white elm ( Ulmns Americana, L.) is a large 

 tree, famous for its grace and beauty in the hands of the landscape - 

 gardener. The Stellaria media (Smith) is the common chickweed, so 

 abundant around dwellings in every part of the world. The stately 

 elm is an American species, as its botanical name indicates, while the 

 chickweed is one of a large class of plants which have come to us un- 

 bidden, and frequently unwelcomed, from beyond the sea. Its greatest 

 economic value seems to be as a salad-plant for canary and other im- 

 prisoned birds. This little, insignificant herb delights in cold, shady 

 soil, and frequently opens its blossoms beneath, or when surrounded 

 by, drifts of snow. There seems to be no good foundation for this 

 haste, as the plant continues in bloom during nearly its whole lifetime 

 of a year or more. It also seems as if it would be just as well to 

 delay flowering until insects are more numerous, at which times the 

 blossoms secrete so much honey that the drops may be seen without a 

 hand-lens. Among other insects, the prolific aphides (plant-lice) and 

 the ubiquitous house-fly (Musca domestica, L.) are attendant upon 

 the unobtrusive chickweed-flowers. The blossoms of the elm are also 

 small, but depend upon the winds for transfer of their pollen. The 

 leaves do not unfold until the flowers are past, and in this circumstance 

 we may see an instance of the working of the law of adaptation. The 

 foliage might interfere with the easy movement of the dry, dusty pol- 

 len from one tree or branch to another. Students of plant-life are 

 always pleased to observe that adaptations for cross-fertilization are 

 worked out along very many lines. The elm offers an instance in 

 which there is a seeming confusion in the floral type. Botanists say 

 the elms are polygamous, which only means that some flowers are per- 



