Jumping point
_(14578104559).jpg)
The term crux was originally coined to denote a biological phenomenon. In this sense, the punctum saliens or the crux of the matter is a pulsating red spot, which can be seen with the naked eye, for example, in the fertilized hen's egg after the third day of incubation, as the first noticeable sign of life: the anlage of the embryo's heart becomes visible, yours physiological function becomes noticeable.
The key point in this picture is the criterion with which living things can be distinguished. This indicative expression goes back to Aristotle , who describes the development in the bird's egg in his animal history and speaks in this context of a bloody point " στιγμὴ αἱματίνη stigmē haimatinē ", which hops " πηδᾷ pēda ".
"Καὶ ὅσον στιγμὴ αἱματίνη ἐν τῷ λευκῷ ἡ καρδία. Τοῦτο δὲ τὸ σημεῖον πηδᾷ καὶ κινεῖται ὥσπερ ἔμψυχον, ... "
“And like a bloody stain in the white the heart [appears]. But the mark hops and moves as if [animated] alive, ... "
In further metaphorical use, a phrase has emerged from this, according to which a crucial point represents the heart of a project, or shows the essential core of a representation, or presents the decisive aspect of a question, or has the criterion for a decision: " There it is".
William Harvey , with his work Exercitatio Anatomica de Motu Cordis et Sanguinis in Animalibus (anatomical studies on the movement of the heart and blood in animals) published in Frankfurt / Main in 1628, the discoverer of the blood circulation , describes in Exercitationes de Generatione Animalium (studies on the Generation of animals) 1651 the biological phenomenon in question as follows:
- “If you examine it like this on the fourth day, the metamorphosis will appear larger and the transformation more admirable; and it becomes more evident almost every hour of that day; at this time the transition from plant life to animal life takes place in the egg. Now the edge of egg white is reddening, turning a thin line a bloody purple color: and almost in the middle of it a bloody point pops out: so tiny that at the moment of his diastole it shines like the smallest spark of fire; and then, in systole, completely escapes the gaze and disappears. So little is the beginning of animal life, so much unnoticed are the beginnings brought about by the creative power of nature! "
- ( »Quarto itaque die si inspexeris, occurret jam major metamorphosis, & permutatio admirabilor; quae singulis fere illius diei horis manifestior fit; quo tempore in ovo, de vita plantae, ad animalis vitam fit transitus. Iam enim colliquamenti limbus linea exili sanguinea purpuras : ejusque in centro fere, punctum sanguineum saliens emicat: exiguum adeo, ut in sua diastole, ceu minima ignis scintillula, effulgeat; & mox, in systole, visum prorsus effugiat, & dispareat.Tantillum nempe est vitae animalis exorduis molitur plastica vis Naturae! " ) According to: Gulielmi Harvei, Opera II, Exercitationes de Generatione Animalium, Leyden 1737, p. 66.
Ernst Haeckel shares a similar view in his essay On the Origin and Development of the Sense Organs of 1878, which presents the results of a comparative anatomy and embryology at that time, as tracing the human eye back to a long series of advantageous adaptations, leaving behind the Aristotelian an afterimage appear:
"The first beginning of the organ of sight in the lower animals is no other than a simple dark spot in the clear integument, generally a black or red pigment spot. Even in the unicellular Protista such dark specks of color-matter seem to serve for the perception of light. "
“The first beginning of the visual organ in the lower animals is nothing more than a simple dark point in the light skin, usually a black or red pigment point. Even with the unicellular protists, such dark spots of dye seem to serve the perception of light. "
Notes and individual references
- ↑ a b quoted from E. Haeckel: The Pedigree of Man: and other Essays . Bonner, London 1903, digitally on archive.org , p. 126 and p. 335 .
- ↑ quoted from Wikisource Των Περί τα Ζώια Ιστοριών