[59] "Each and every plant is at first a cell."--"New cells can never be formed externally to, but only within, other cells already formed." (A. Braun, on the Veg. Indiv.) "The process of the propagation of cells, by the formation of new cells in their interior, is an universal law in the vegetable kingdom." (Schleiden; Grundzuege). "Cell-formation in plants takes place only in the cavities of older cells." (Mohl, on the Veg. Cell) [60] See Von Martius, on the Brazilian Locusts. [61] The origin of coral-stocks is minutely described by Ehrenberg, in the Abhandl. for 1832, where he makes the following remarks:--"The coral mass is neither a mere structure composed of many animals arbitrarily conjoined, as Ellis supposed; nor one single animal with many heads, or with simple furcations, as Cavolini maintained; nor a vegetable stem with animal flowers, as Linnaeus expressed it; it is a body of families, a _living_ tree of consanguinity; the single animals belonging to it, and continually developing _upon the primary ancestor_, are entirely isolated within themselves, and capable of complete independence, _although unable to achieve it_." [62] This is not quite in accord with Lamouroux's account; but it is more consistent with what we know of polype-growth. [63] We lack precise data on which to found conclusions as to the actual rate of growth of many animals. Sir John Dalyell's famous Actinia, now in the possession of Dr. Fleming, affords us a proof that the Zoophytes are long-lived, and slow in attaining maturity. It will be readily seen, however, that the argument in the text does not depend on the actual period evolved. The lapse of _a_ period of time, no matter how long, is the only essential point. [64] "All the component cells of any one organism may be considered as the descendants of the primordial cell in which it originated." (_Dr. Carpenter_; Comp. Physiol.; p. 396. 4th Ed.) [65] I conclude so; because I have kept specimens of _Echinus_, not full grown, in healthy condition, for nearly a year, without any perceptible increase in their dimensions. [66] I am not aware that this stage of the Entozoon has been actually observed; but from what we know of its previous and subsequent history, the correctness of the statement in the text will scarcely be disputed. (See Prof. Owen: Comp. Anat. of Inverteb. Ed. 2. p. 74.) [67] See Notes to "Marmion." [68] Report on Brit. Annelida, p. 194. [69] We have no direct observations, that I am aware of, on the larval state of the African _Goliathi_; but their near ally, the _Cetonia aurata_ of Europe, passes four years in the grub condition, as does also the _Melolontha vulgaris_, another lamellicorn beetle. The _Lucanus cervus_, or Stag-beetle, continues a larva for six years. [70] Fabre; Ann. d. Sci. Nat.; iii. 1855. [71] _B. splendida_, has been ascertained to have existed, as an inmate of the wood of a table, for _more than twenty_ years. (Linn. Trans.; x. 399.)