Page:Popular Science Monthly Volume 50.djvu/114

102 the whole duration of vegetation, and continues at the time of flowering, which, without doubt, by a mechanism of which we do not know the method of operation, takes place only when the quantity of materials elaborated is sufficient to nourish the seeds which are about to appear.

The wheat begins to head, in our latitude, early in June. On pressing lightly between the fingers the upper part of the stem, at the place where it appears a little swollen, we meet a slight resistance, due to the head, which is entirely formed before it emerges. It is composed of a stem; the rhachis, which bears the flowers, formed of little green leaflets; and the glumes, one of which terminates, in some varieties, in the long appendage characteristic of bearded wheat. If, at the moment when the head emerges outside of the stem, we gently lay open the glumes, we shall discover the essential organs of the flower within. On a little greenish swelling, the rudiment of the corn, are fixed two little aigrettes of plumes, slightly divergent. These are the pistils, the female organs. Around them, fixed at the extremity of fine peduncles, are the anthers, as yet closed. They contain the pollen, the yellow fecundating dust. At the moment of maturity the anthers open and the pollen falls on the little plumes of pistils, well constructed to hold it. It germinates there, sends out a long tube—the pollinical branch—into the ovule, to which the plumous pistils are attached. Fecundation is accomplished, and the corn is formed.

All these delicate operations, which it is so interesting to follow, take place in the formed flower. When the stamens, emerging between the glumelles, appear without, or, to use the common expression, the wheat is in flower, everything is really done. So, when we try to create hybrids—that is, new varieties—endowed with qualities wanting in one of the parents, we must take the anthers from the flowers before the plumes are open and the anthers have shed their pollen.

The operation exacts much care. When the flower is half opened, we cut off the anthers it contains and drop in the pollen of the variety which we have chosen to give the one we operated upon the qualities which it lacks. One of the most widely distributed varieties around Paris, the Dattel, was created in this way by M. H. de Vilmerin by fecundating the pistils of the English Chiddam wheat, which had fine qualities but a short straw, with the pollen of the Prince Albert wheat. The operation was perfectly successful; the straw of the Dattel is thicker and longer by at least five inches than that of the Chiddam, from which it is derived. The variety is quite fixed; it reproduces itself with well-defined characteristics; and the experiment has now been of long enough duration to make it certain that the seed sown is not