Biology and Its Makers / With Portraits and Other Illustrations

by William A. Locy

The Period of Harvey and Malpighi

In General.—The usual account of the rise of embryology is derived from German writers. But there is reason to depart from their traditions, in which Wolff is heralded as its founder, and the one central figure prior to Pander and Von Baer.

The embryological work of Wolff's great predecessors, Harvey and Malpighi, has been passed over too lightly. Although these men have received ample recognition in closely related fields of investigation, their insight into those mysterious events that culminate in the formation of a new animal has been rarely appreciated. Now and then a few writers, as Brooks and Whitman, have pointed out the great worth of Harvey's work in embryology, but fewer have spoken for Malpighi in this connection. Koelliker, it is true, in his address at the unveiling of the statue of Malpighi, in his native town of Crevalcuore, in 1894, gives him well-merited recognition as the founder of embryology, and the late Sir Michael Foster has written in a similar vein in his delightful Lectures on the History of Physiology.

However great was Harvey's work in embryology, I venture to say that Malpighi's was greater when considered as a piece of observation. Harvey's work is more philosophical; he discusses the nature of development, and shows unusual powers as an accurate reasoner. But that part of his treatise devoted to observation is far less extensive and exact than Malpighi's, and throughout his lengthy discussions he has the flavor of the ancients.

Malpighi's work, on the contrary, flavors more of the moderns. In terse descriptions, and with many sketches, he shows the changes in the hen's egg from the close of the first day of development onward.

It is a noteworthy fact that, at the period in which he lived, Malpighi could so successfully curb the tendency to indulge in wordy disquisitions, and that he was satisfied to observe carefully, and tell his story in a simple way. This quality of mind is rare. As Emerson has said: "I am impressed with the fact that the greatest thing a human soul ever does in this world is to see something, and tell what it saw in a plain way. Hundreds of people can talk for one who can think, but thousands can think for one who can see. To see clearly is poetry, philosophy, and religion all in one." But "to see" here means, of course, to interpret as well as to observe.

Although there were observers in the field of embryology before Harvey, little of substantial value had been produced. The earliest attempts were vague and uncritical, embracing only fragmentary views of the more obvious features of body-formation. Nor, indeed, should we look for much advance in the field of embryology even in Harvey's time. The reason for this will become obvious when we remember that the renewal of independent observation had just been brought about in the preceding century by Vesalius, and that Harvey himself was one of the pioneers in the intellectual awakening. Studies on the development of the body are specialized, involving observations on minute structures and recondite processes, and must, therefore, wait upon considerable advances in anatomy and physiology. Accordingly, the science of embryology was of late development.

Harvey.—Harvey's was the first attempt to make a critical analysis of the process of development, and that he did not attain more was not owing to limitations of his powers of discernment, but to the necessity of building on the general level of the science of his time, and, further, to his lack of instruments of observation and technique. Nevertheless, Harvey may be considered as having made the first independent advance in embryology.

By clearly teaching, on the basis of his own observations, the gradual formation of the body by aggregation of its parts, he anticipated Wolff. This doctrine came to be known under the title of "epigenesis," but Harvey's epigenesis[3] was not, as Wolff's was, directed against a theory of pre-delineation of the parts of the embryo, but against the ideas of the medical men of the time regarding the metamorphosis of germinal elements. It lacked, therefore, the dramatic setting which surrounded the work of Wolff in the next century. Had the doctrine of pre-formation been current in Harvey's time, we are quite justified in assuming that he would have assailed it as vigorously as did Wolff.