One of these men—Malpighi—was an Italian, and the other two were Netherlands Dutchmen. Their great service "consisted chiefly in this, that they broke away from the thraldom of book-learning, and, relying alone upon their own eyes and their own judgment, won for man that which had been quite lost, the blessing of independent and unbiased observation." The importance of this step for its broad-reaching effects even upon the intellectual life of our own time is not easily overestimated. Much of the work of the present is built upon the foundations they laid.
There is a singularly unappreciative attitude towards scientific work, of the biological kind, done before 1850, and a widespread disposition to look upon the advances of the present time as peculiarly our own, based wholly upon 'modern' work and 'modern' methods. This sometimes takes the extreme form, in the rising generation of practical workers, of looking upon the scientific investigations of the past ten years as of necessarily better quality than those of any preceding period, because they are the most recent. But this is to do injustice to our predecessors, and it is wholesome to take a look into the past, to see some of the fine observational work done long ago, and to be compelled to recognize the continuity of biological development, both as regards work and ideas.
If it were Johannes Müller with whom we were to deal, a marvel could be shown, but the work of Malpighi. Swammerdam and Leeuwenhoek belongs to a period a century and a half before his time. For these men it is just to claim, in addition to the service indicated above, the possession of the true scientific spirit, the introduction of the microscope and of more exact methods into scientific investigation, and, through their work, the beginning of that better comprehension of the natural universe that we call modern science.
It is natural that working when they did, and independently as they did, their work overlapped in many ways. Malpighi is noteworthy for many discoveries in anatomical science, for his monograph on the anatomy of the silkworm, for observations on the minute structure of plants and on the development of the chick in the hen's egg. Together with Grew, he is regarded as the founder of plant histology. Swammerdam did excellent and accurate work on the anatomy and metamorphosis of insects and the internal structure of mollusks, frogs and other animals. Leeuwenhoek is distinguished for much general microscopic work; he discovered various microscopic animalcula; he established by direct observation a connection between arteries and veins, and examined microscopically minerals, plants and animals. To him more than to the others the general title of 'microscopist' might be applied.
Let us, by taking them individually, look a little more closely at the lives and labors of these men.
