The "Concept of Organism" and the Relation Between Embryology and Genetics. Part I

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Abstract
Though biologists know much of the material tools of their subject they lack familiarity with their intellectual tools, i.e., they do not understand the nature of their knowledge. They need a better grasp of the fundamental concepts involved in their reasoning, and also certain new concepts. This is why they have only biological theories and no theoretical biology comparable with theoretical physics. The "concept of organism" proposed by Schaxel and again advocated by Haldane furnishes one of the new viewpoints important for the elaboration of such a biology. This new concept is a departure from that of the organism as a machine derived from Descartes, and involves certain subsidiary notions such as the "organic whole," "organic part," and "organic relation." To these is added a concept of "hierarchical order" which seems to mean essentially that the parts of an organism may be divided and subdivided both spatially and temporally into various classes and subclasses extending from the whole down to the various chemical elements. It also emphasizes the idea that the character of the whole is very largely dependent on the relation of the parts to one another. The generation of such an order occurs during development, and is the problem of the experimental embryologist and geneticist. After an analysis of the principle of causation the writer attempts to see how it applies to the embryologi-cal problem as viewed by one who adheres to the concept of organism. On this basis the development of any particular character depends 1st upon the existence in the coll nuclei of genes possessing certain "intrinsic" properties, i.e., properties common to all the nuclei in any organism which shows the character. The occurrence of the character then further depends upon the special relations of the particular cells involved, to whose cytoplasm there is thus imparted peculiar "relational" properties. The assumption of such cytoplas-mic relational properties is made necessary by the current belief that all the nuclei in an organism contain the same kind of genes. For unless one abandons the causal postulate entirely, or appeals either to chance environmental differences or to transcendental factors, there is no other means of accounting for differentiation. This makes apparently impossible the postulation of a completely "equipotential system" at any stage in development. Thus initially the egg cytoplasm must have some relational differences or the elaboration of parts could never start. Whether there really are no equipotential systems among organisms, and whether the slight cytoplasmic differentiation in the egg is sufficient to account for all that follows, remains to be discovered.

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