[7] The following extract from 'An Examination of Weismannism,' pp. 2, 3, will possibly explain the theory of Pangenesis, which assumes: 1. That all the component cells of a multicellular organism throw off inconceivably minute germs, or 'gemmules,' which are then dispersed throughout the whole system. 2. That these gemmules, when so dispersed and supplied with proper nutriment, multiply by self-division, and, under suitable conditions, are capable of developing into physiological cells like those from which they were originally and severally derived. 3. That, while still in this gemmular condition, these cell-seeds have for one another a mutual affinity, which leads to their being collected from all parts of the system by the reproductive glands of the organism; and that, when so collected, they go to constitute the essential material of the sexual elements--ova and spermatozoa being thus aggregated packets of gemmules, which have emanated from all the cells of all the tissues of the organism. 4. That the development of a new organism out of the fusion of two such packets of gemmules is due to a summation of all the developments of some of the gemmules which these two packets contain. 5. That a large proportional number of the gemmules in each packet, however, fail to develop, and are then transmitted in a dormant state to future generations, in any of which they may be developed subsequently, thus giving rise to the phenomena of reversion or atavism. 6. That in all cases the development of gemmules into the form of their parent cells depends on their suitable union with other partially developed gemmules which precede them in the regular course of growth. 7. That gemmules are thrown off by all physiological cells, not only during the adult state of the organism, but during all stages of its development. Or, in other words, that the production of these cell-seeds depends upon the adult condition of parent cells, not upon that of the multicellular organism as a whole. [8] The experiments in graft-hybridisation were to prove that formative material (or gemmules) was actually present in the general tissues of plants and was capable of uniting with the gemmules of another plant and thus of reproducing the entire organism. For if the hybrid, afterwards produced, presents equally the characters of the scion and the stock, then formative material must have been present in the tissues of the scion, and it is demonstrated that the somatic tissues of the scion have exercised an effect on the germinal elements of the stock, inasmuch as it has caused their offspring in part to resemble it. Such facts Romanes considered to be fully in harmony with the theory of Pangenesis, and inconsistent with any theory which supposes that _no_ part of the parent organism generates _any_ of the formative material. [9] To the Royal Society. [10] For the Suppression of Vivisection. [11] Mr. Grant Allen. [12] Spiritualism.