For the first few years after this discovery Pasteur endeavored by every possible means to secure experimental modifications of some of these phenomena of dissymmetry. He hoped thus to learn more fully their true nature. Magnetic influences especially would, he hoped, enable him to pierce, at least to some degree, this fundamental mystery of nature. While acting as professor at Strasburg, he procured powerful magnets with the view of comparing the actions of their poles and, if possible, of introducing by their aid among the forms of crystals a manifestation of dissymmetry. At Lille, where he was for several years dean of the scientific faculty, he contrived a piece of clockwork intended {302} to keep a plant in continual rotary motion, first in one direction and then in the other. "All this was crude," he says himself, "but further than this I had proposed with the view of influencing the vegetation of certain plants to invert, by means of a heliostat and a reflecting mirror, the motion of the solar rays which should strike them from the birth of their earliest shoots. In this direction there was more to be hoped for." He did not have time, however, to follow out these ingenious experiments. He became involved, as we shall see, in labors more than sufficient to take up all his time and all his energy. These labors were of great practical importance for France. Pasteur always insisted, however, that great discoveries will yet be made in following out this order of ideas, and that there is in this subject magnificent opportunity for young men possessed of the genius of discovery and the power of persistent work.