If the integrity of the organism sustains an injury in consequence of abnormal interferences, determinants develop exceptionally at unusual points. The process is induced by accumulation of nutritive matter and by external stimuli under the force of necessity, to which the injured organism is sensible.
14. ESSENTIAL NATURE OF THE ORGANISM.
The essential nature of a thing is the sum total of its causes and effects. Organisms arise from a germ cell which consists of idioplasm and in turn they produce like germ cells. Their nature depends also on their idioplasm, i.e., on the sum total of their idioplasmic determinants. Observation of organisms, even in their fullest life history, gives us an imperfect and even false conception of their true nature. This is because observation reveals only the outer gross characters, and even these in a modification dependent upon accidental effects of nutrition, and does not reveal the finer characters founded in molecular physiology and morphology, and especially the characters latent in the idioplasm.
For the examination of idioplasmic differences we are restricted to visible characters. Hence a knowledge of the nature of an organism presupposes a complete investigation of its characters in their succession during the whole ontogeny. The results must, however, be tested and completed by comparison with other organisms and by the most comprehensive experimental procedure, possible, (as by culture under various conditions, and crossing with nearer and more remote relatives). The characteristics of nutrition varieties and accidental crosses must be separated from specific characteristics by experimental procedure, and latent determinants must be brought out by the same means.
15. REPRODUCTION, AND RELATION BETWEEN PARENTS AND OFFSPRING.
Reproduction is nothing more than a transition from one generation to the next following, mediated by the idioplasm of the germ cell. In asexual (monogenic) reproduction there is continuity of the same idioplasm. Therefore the parent continues in the offspring its specific life, as the stem continues its specific life in the branch. All the peculiarities conditioned by the idioplasm remain unchanged in the offspring. The latter, as the immediate continuation of the preceding ontogeny, starts from the point at which the germ cell left it, so that immediately after the germ cell is separated at the close of the ontogeny or before, the offspring passes at one time rapidly through the whole ontogeny, at another only the remainder or a part of it (the latter in alternation of generations and in asexual propagation of phanerogams).
In sexual (digenic) reproduction the formation of the germ cell is brought about by the union in equal parts of both parental idioplasms. The offspring is the organism resulting from the union of the force and matter of the parents, and represents in its nature the united continuation of their ontogenies. The characteristics of development of the child depend however on the viability of the determinants of the mingled idioplasms in which a new equilibrium has been formed. Hence if the child bears more resemblance to the father or to the mother, it follows that some of the inherited determinants develop while the others remain latent. If the child has certain visible characteristics more marked than either parent, it becomes possible only by the development of determinants which had previously been latent. The fact that the mother furnishes the germ cell with nutritive plasm and that she nourishes it for a considerable time does not increase the number of maternal determinants nor their capability of development.
If two corresponding characters, one derived from the father, the other from the mother, come into conflict in sexual reproduction, the one or the other, or even a third alternative characteristic, which heretofore was present as a latent determinant, may develop in the child. But also both parental characters may appear at once and in various combinations. Whether the development follows in the one way or the other depends on the strength of the individual determinants, on the kind of their idioplasmic arrangement, and on their agreement with the nature of the newly formed idioplasm.
16. HEREDITY AND VARIATION.
If heredity and variation are defined according to the true nature of organisms, they are only apparent opposites. Since idioplasm alone is transmitted from one ontogeny to the next following, the phylogenetic development consists solely in the continual progress of the idioplasm and the whole genealogical tree from the primordial drop of plasma up to the organism of the present day (plant or animal) is, strictly speaking, nothing else than an individual consisting of idioplasm, which at each ontogeny forms a new individual body, corresponding to its advance.