CULT,- FORMATION.

119

different conclusion. In the very first place comes thequestion, what import may be attributed to those obser-vations which represent the secondary cells free withinthe parent-cells, as Schleiden ’s in the germinating sporeof Marchantia * * * § in the hairs of the ovary of lupinus, +in the terminal shoot of Opuntia t % in the pollen-tube, andin other cells, § and my own in the apex of the root ofLilium. || As to my own earlier investigations, they be-long to an epoch (autumn 1841, and spring 1842,)when I was yet unacquainted with the mucilaginouslayer. When I discovered it, in the summer of 1842,at Naples, in Algae and Floridese, and subsequently re-found it in other vegetable-cells, I soon became convincedthat my earlier researches were doubtful, since that which1 had held to be the cell-membrane might in every casehave been the mucilaginous layer.

With regard to the facts published by Schleiden , Ilikewise believe that the explanation given by him is byno means placed beyond all doubt. In the first place,cell-formation in the pollen-tube cannot prove anythingfor other cell-formation; since here two thoroughly dif-ferent kinds of cell-formation, one of which is transitorywhile the other produces the embryo, have not yet beennearly sufficiently discriminated. The cell-formation inthe spore of Marchantia , I must, from certain researchesof my own on the germination of the Hepaticse, hold tobe incorrect; and conjecture that a confusion has occurredwith the accidental formation of utricles, such as some-times happens in cells. With respect to the rest of theobservations published by Schleiden , it must be borne inmind that he also makes no distinction between cell-membrane and mucilaginous layer; so that the interpre-tation is always possible, that the apparently free secondary

* Muller’s Arcliiv, 1838, Tab. iii, figs. 19, 20.

f Acta Ac. C. L. C. Nat. Cur., vol. xix, p. 1, pi. x, fig. 38 e.

+ Mem. de l’Acad. Imp. d. Sc. de St. Petersbourg, VI Serie, vol. iv,pi. viii, fig. 9.

§ Grundz. 2d Ed. pi. i, figs. 12 and 16.

|| Linnaja, 1842, PI. ix, figs. 30, 31.