Much more important, however, for subsequent biological development than such observations on the nature and habits of animals, is the service that the Hippocratic physicians rendered to Anatomy and to Physiology, departments in which the structure of man and of the domesticated animals stands apart from that of the rest of the animal kingdom. It is with the nature and constitution of man that most of the surviving early biological writings are concerned, and in these departments are unmistakable tendencies towards systematic arrangement of the material. Thus we have division and description of the body in sevens from the periphery to the centre and from the vertex to the sole of the foot,[9] or a division into four regions or zones.[10] The teaching concerning the four elements and four humours too became of great importance and some of it was later adopted by Aristotle. We also meet numerous mechanical explanations of bodily structures, comparisons between anatomical conditions encountered in related animals, experiments on living creatures,[11] systematic incubation of hen's eggs for the study of their development, parallels drawn between the development of plants and of human and animal embryos, theories of generation, among which is that which was afterwards called 'pangenesis'--discussion of the survival of the stronger over the weaker--almost our survival of the fittest--and a theory of inheritance of acquired characters.[12] All these things show not only extensive knowledge but also an attempt to apply such knowledge to human needs. When we consider how even in later centuries biology was linked with medicine, and how powerful and fundamental was the influence of the Hippocratic writings, not only on their immediate successors in antiquity, but also on the Middle Ages and right into the nineteenth century, we shall recognize the significance of these developments. [9] περι ἑβδομαδων {peri hebdomadôn}. The Greek text is lost. We have, however, an early and barbarous Latin translation, and there has recently been printed an Arabic commentary. G. Bergstrasser, _Pseudogaleni in Hippocratis de septimanis commentarium ab Hunnino Q. F. arabice versum_, Leipzig, 1914. [10] περι νουσων δ {peri nousôn d}. [11] περι καρδιης {peri kardiês}. [12] Especially in the περι γονης {peri gonês}. [Illustration: Fig. 5. MINOAN GOLD CUP. SIXTEENTH CENTURY B. C.] [Illustration: Fig. 6. HORSE'S HEAD. FROM PARTHENON. 440 B. C.]