Chapter VIII – Natural Philosophy. The Organic World (Concluded)
Engels gives a description of the nature of organic bodies, consisting of cells. He, then, describes the cell, consisting of a nucleus and outer membrane containing liquid surrounding the nucleus. Engels notes the existence of single celled organisms, as the most basic forms of life, and of the development of multi-celled organisms. He describes the process of cell division, but could not, at that time, explain how the evolution from single-celled to multi-cellular organisms occurred, because science has only recently proposed a theory to explain that.
The process of the formation of living organisms from non-living matter, abiogenesis, is, now, fairly well understood. The “vital spark”, is not itself some mystical act of creation, but arises from purely natural processes, combining known chemicals, and the role of electricity generated from a proton gradient.
The whole of Engels' presentation was necessarily limited, as he says, by the limits of science at that time. Not only had DNA and RNA not been discovered, but all of the science related to genes, in the type of cells produced to perform given functions was not known. So, although Engels could describe the way that all of the organic elements such as bones, blood, skin and so on are comprised of cells, and these cells are all different, he could not explain what causes that process of cell division to produce some cells that are blood cells, some bone cells, and some skin cells, for example, given that they begin from a single cell.
However, even allowing for those inevitable deficiencies, the point is that the process of cell division and formation of organic material, described by Engels, is clearly one of the development of the organism. Indeed, embryology, in looking at the development of the human embryo, in the womb, notes the similarities with other forms of embryo, reflecting the common heritage and evolution of all life. The main point, here, is in contrast to Duhring's description of this process as “composition”, implying some conscious or pre-determined end, that was involved, rather than development, which evolutionary theory shows takes place unconsciously, and with no pre-determined end, and yet, still purposively.
Engels quotes Duhring's definition of life.
“The inorganic world too is a system of automatic movements; but it is only at the point where real differentiation, and the interposition of the circulation of substances through special channels from one internal point and according to an embryonic scheme transmissible to a smaller structure begins that we may venture to speak of real life in the narrower and stricter sense”. (p 97)
Engels notes that this makes no logical or grammatical sense.
“If life first begins where real differentiation commences, we must declare that the whole Haeckelian kingdom of protista and perhaps much else besides to be dead, according to the meaning we attach to the concept of differentiation. If life only begins when this differentiation can be transmitted through a smaller embryonic scheme, then at least all organisms up to and including unicellular ones are not living things. If the interposition of the circulation of substances through special channels is the distinguishing mark of life, then, in addition to the foregoing, we must strike from the ranks of the living the whole of the higher class of the Coelenterata (excepting however the Medusae), that is, all polyps and other plant-animals. If the circulation of substances through special channels from one internal point is the essential characteristic of life, then we must declare that all those animals which have no heart and those which have more than one heart are dead. That is besides those already enumerated, all worms, starfish and rotifers (Annuloida and Annulosa, Huxley's classification), a section of the Crustacea (lobsters), and finally even a vertebrate animal, the Amphioxus. And moreover all plants.” (p 97-8)
Haeckel's theory of these pre-cellular organisms was deficient, but science has confirmed the development of cellular organisms from pre-cellular organisms.
No comments:
Post a Comment