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says :1 “
Excessively minute and numerous as they are believed to be, an infinite number derived, during a long course of modification and descent, from each cell of each progenitor, could not be supported and nourished by the organism."
But apart from these matters, which will be more fully considered further on, the hypothesis not only does not appear to account for certain phenomena which, in order to be a valid theory, it ought to account for; hut it seems absolutely to conflict with patent and notorious facts.
How, for example, does it explain the peculiar reproduction which is found to take place in certain marine worms --certain annelids?
In such creatures we see that, from time to time, one of the segments of the body gradually becomes modified till it assumes the condition of a head, and this remarkable phenomenon is repeated again and again, the body of the worm thus multiplying serially into new individuals which successively detach themselves from the older portion. The development of such a mode of reproduction by
Natural Selection " seems not less inexplicable than does its continued performance through the aid of “pangenesis." For how can gemmules attach themselves to others to which they do not normally or generally succeed? Scarcely less difficult to understand is the process of the stomach-carrying-off mode of metamorphosis before spoken of as existing in the Echinoderms. Next, as to certain patent and notorious facts: On the bypothesis of pangenesis, no creature can develop an organ unless it possesses the component gemmules which serve for its formation. No creature can possess such gemmules unless
1 “Animals and Plants under Domestication,” vol. ii. 402.
it inherits them from its parents, grandparents, or its less remote ancestors. Now, the Jews are remarkably scrupulous as to marriage, and rarely contract such a union with individuals not of their own race. This practice has gone on for thousands of years; and similarly also for
AN ANNELID DIVIDING SPONTANEOUSLY (A new head having been forined towards the hinder end of the body of the parent).
thousands of years the rite of circumcision has been unfailingly and carefully performed. If then the hypothesis of pangenesis is well founded, that rite ought to be now absolutely or nearly superfluous from the necessarily
continuous absence of certain gemmules through so many centuries and so many generations. Yet it is not at all so, and this fact seems to amount almost to an experimental demonstration that the hypothesis of pangenesis is an insufficient explanation of individual evolution.
Two exceedingly good criticisms of Mr. Darwin's hypothesis have appeared. One of these is by Mr. G. H. Lewes, the other by Professor Delpino of Florence. The latter gentleman gives a report of an observation made by him upon a certain plant, which observation adds force to what has just been said about the Jewish race. He says : 3 “If we examine and compare the numerous species of the genus Salvia, commencing with Salvia officinalis, which may pass as the main state of the genus, and concluding with Salvia verticillata, which may be taken as the most highly developed form, and as the most distant from the type, we observe a singular phenomenon. The lower cell of each of the two fertile anthers, which is much reduced and different from the superior even in Salvia officinalis, is transmuted in other salvic into an organ (nectarotheca) having a very different form and function, and finally disappears entirely in Salvia verticillata.”
Now, on one occasion, in a flower belonging to an individual of Salvia verticillata, and only on the left stamen, I observed a perfectly developed and pollinigerous lower cell, perfectly homologous with that which is normally developed in Salvia officinalis. This case of atavism is
1 See Fortnightly Review, New Series, vol. iii. April 1868, p. 352.
2 This appeared in the Rivista Contemporanea Nazionale Italiana, and was translated and given to the English public in Scientific Opinion of September 29, October 6, and October 13, 1869, pp. 365, 391, and 407.
See Scientific Opinion of October 13, 1869, p. 407.
truly singular. According to the theory of Pangenesis, it is necessary to assume that all the gemmules of this anomalous formation, and therefore the mother-gemmule of the cell, and the daughter-gemmules of the special epidermic tissue, and of the very singular subjacent tissue of the endothecium, have been perpetuated, and transmitted from parent to offspring in a dormant state, and through a number of generations, such as startles the imagination, and leads it to refuse its consent to the theory of Pangenesis, however seductive it may be.” This seems a further confirmation of what has been advanced as to the Jews.
The main objection raised against Mr. Darwin's hypothesis is that it (Pangenesis) requires so many subordinate hypotheses for its support, and that some of these are not tenable.
Professor Delpino considers that as many as eight of these subordinate hypotheses are required, namely, that
“1. The emission of the gemmules takes place, or may take place, in all states of the cell.”
“2. The quantity of gemmules emitted from every cell is very great."
“ 3. The minuteness of the gemmules is extreme.”
“4. The gemmules possess two sorts of affinity, one of which might be called propagative, and the other germinative affinity.
“5. By means of the propagative affinity all the gemmules emitted by all the cells of the individual flow together and become condensed in the cells which compose the sexual organs, whether male or female (embryonal vesicle, cells of the embryo, pollen grains, fovilla, antherozoids, spermatozoids), and likewise flow together and be1 See Scientific Opinion of September 29, 1869, p. 366.
come condensed in the cells which constitute the organs of a sexual or agamic reproduction (buds, spores, bulbilli, portions of the body separated by scission, &c.).”
“6. By means of the germinative affinity, every gemmule (except in cases of anomalies or monstrosities) can be developed only in cells homologous with the mother-cells of the cell from which they originated. In other words, the gemmules from any cell can only be developed in unison with the cell preceding it in due order of succession, and whilst in a nascent state.”
“ 7. Of each kind of gemmule a great number perishes; a great number remains in a dormant state through many generations in the bodies of descendants; the remainder germinate and reproduce the mother-cell.”
“8. Every gemmule may multiply itself by a process of scission into any number of equivalent gemmules.
Mr. Darwin has published a short notice in reply to Professor Delpino, in Scientific Opinion of October 20, 1869, p. 426. In this reply he admits the justice of Professor Delpino's attack, but objects to the alleged necessity of the first subordinate hypothesis, namely, “ that the emission of gemmules takes place in all states of the cell." But if this is not the case, then a great part of the utility and distinction of Pangenesis is destroyed, or, as Mr. Lewes justly says:1 “If gemmules produce whole cells, we have the very power which was pronounced mysterious in larger organisms.”
Mr. Darwin also does not see the force of the objection to the power of self-division which must be asserted of the gemmules themselves if Pangenesis be true. The objection, however, appears to many to be a serious one.
Fortnightly Review, New Series, vol. iii. April 1868, p. 508.