Page:Popular Science Monthly Volume 67.djvu/107

Rh spot or cicatricula. He also corrected Aristotle, Fabricius and his other predecessors in many particulars.

Harvey's greatest predecessor in this field, Fabricius, was also his teacher. When, in search of the best training in medicine, Harvey wended his way from England to Italy, in Padua, he came under Fabricius as one of his teachers. In 1600, Fabricius published the earliest illustrations on the development of animals, and, again, in 1625, six years after his death, appeared his illustrated treatise on the development of the chick Altogether his figures show developmental stages of the cow, sheep, pig, galeus, serpent, rat and chick. The value of his work may be easily overestimated by a casual examination of the plates.

Harvey's own treatise was not illustrated. With that singular independence of mind which he showed in all his work, the vision of the pupil was not hampered by the authority of his teacher, and, trusting only to his own sure observation and reason, he described the stages of development as he saw them in the egg, and placed his own construction on the facts.

One of the earliest things to arrest his attention in the chick was a pulsating point, the heart, and, from this observation, he supposed that the heart and blood were the first formations. He says: "But as soon as the egg, under the influence of the gentle warmth of the incubating hen, or of warmth derived from another source, begins to pullulate, this spot forthwith dilates, and expands like the pupil of the eye, and from thence, as the grand center of the egg, the latent plastic force breaks forth and germinates. This first commencement of the chick, however, so far as I am aware, has not yet been observed by any one."

It is to be understood, however, that his descriptive part is relatively brief (about 40 pages out of 350 in Willis's translation), and that the bulk of the 106 'exercises' into which his work is divided is devoted to comments on the older writers and discussions of the nature of the process of development.

Portraits of Harvey are by no means uncommon. The one in the National Portrait Gallery, in London, is represented in Fig. 1. This is usually regarded as the second-best portrait of Harvey, since the one painted by Jansen, now in possession of the Royal College of Physicians, is believed to be the best one extant. Permission to reproduce the latter is not given.

The picture in the National Gallery shows a countenance of composed intellectual strength, with a suggestion, in the forehead and outline of the face, of some of the portraits of Shakespeare.

The aphorism Omne vivum ex ovo though not invented by