THE EVIDENCE FROM DEVELOPMENT. 169 



life ? " the investigation of the life-histories of animals and plants is 

 fraught with high importance in another sense and in other aspects 

 of the scientific interpretation of nature. The early observers hardly 

 imagined that, in their researches into the formation of the chick, they 

 were laying the foundation of a study which in future days would be 

 destined to aid man's comprehension of his own origin and that of 

 all other living beings. Aristotle's observations upon the developing 

 chick, and his bestowal of the name punctum safaris, or " beating 

 point," upon the first beginnings of the heart in the embryo bird, were 

 in truth fraught with an importance to succeeding generations which 

 that philosopher could barely have realised had he possessed any 

 prophetic foresight whatever. And no less would Harvey himself 

 have been astonished had he beheld the results to which the pursuit 

 of his favourite study has led in these latter days. It was that great 

 philosopher himself who first maintained that the chick was developed, 

 not from the white of the egg, but from a minute speck or scar on 

 the surface of the yolk, known as the blastoderm or dcatricula. In 

 felicitous terms Harvey enunciates his opinion that the " Medici," 

 or disciples of Galen and Hippocrates, were in error when they sup- 

 posed that such important structures as brain, heart, and liver were 

 first produced, simultaneously, as minute sacs or vesicles ; and he 

 disagrees with Aristotle, in respect that the latter had maintained the 

 punctum s aliens [or punctum sanguineum\, or heart, as the chief agent 

 in forming the structures of the new being. Harvey ascribed to the 

 blood itself the formative power in developing the chick. With 

 Aristotle, however, Harvey is in perfect agreement in believing that 

 the chick is formed, not by the sudden formation of new parts outside 

 the already formed organs, nor by the growth of a miniature and 

 perfectly formed embryo into the larger chick, but by the gradual 

 development and elaboration of uniform and like matter into the 

 new and varied parts and organs of the bird. 



Such were Harvey's views regarding the nature of development. 

 Of the supreme interest exhibited by the discoverer of the circula- 

 tion in this study, no better proof could be cited than his own words 

 when he maintains " that it is most apparent that, in the generation of 

 the chicken out of the egge, all things are set up and formed with a 

 most singular providence, Divine wisdom, and an admirable and 

 incomprehensible artifice." Harvey's doctrine of development re- 

 ceived the name of Epigenesis, which the physiologist himself defines, 

 in his forty-first " Exercitatron," as " the additament of parts bud- 

 ding one out of another." Contrasted with this opinion, is that 

 of such physiologists as Malpighi and Leibnitz. They held that 

 the body of the chick could be traced in the egg before the first 

 rudiment of the heart appeared ; and that from the first formation of 

 the egg, and prior to incubation, the young bird was to be found 



