116

■VEGETABLE CELLS.

which has been formed as an after-growth in the cell.We are acquainted with such secondary nuclei in theparent-cells of spores and pollen-granules, and in thespore- and pollen-cells themselves.* In these, however,there is also a primary nucleus. The two nuclei lie sideby side in their cell; or the primary nucleus becomesdissolved when the secondary is produced. In the casesreferred to, the primary nucleus is parietal, the secondaryfree. Now, as regards the nuclei in the germ-cells of theAlgae, Lichens, and Fungi, in some I found a distinctlyparietal position. I conjecture, therefore, already on thesegrounds, that they are primary nuclei, and, consequently,that a nucleus exists in the origin of the germ-cells. Thisconjecture is supported by another reason. In the sectionon the nucleus,f I demonstrated that if any conclusionfrom analogy at all be permitted, it must be assumed thatevery vegetable-cell possesses a nucleus, at least in theearly stages of its existence. It is, therefore, in thehighest degree probable that a nucleus is present in thecell originating by normal cell-formation, and this at theactual time of its origin. This argument is still furtherborne out by the fact that sometimes, in plants where nonucleus is visible in the formation of the germ-cells, allthe succeeding cells are developed under the influence ofnuclei. Now it seems to me very improbable here thatthe vegetative cell-formation should take place throughnuclei, and the reproductive cell-formation without, that,consequently, the lower cell-formation should presentgreater complexity, and the higher be the more simple.It is further to be remarked, that the assumption thatgerm-cells originate like endosperm-cells around nuclei,may be connected with the visible phenomena withoutstretching any point. In both places, globules of muci-lage first present themselves, which gradually enlarge, andat last appear as granular cells. In the endosperm-cells,the nuclei may be distinguished and recognised as such,

* Part I, Bay Translation, p. 247. % Ibid., pp. 219 et seq., and 246.