CELL-FORMATION.

135

Schleiden was the first to express the formation of cellsin cells as the universal law for vegetables. In manyresearches on the most diverse orders of the vegetablekingdom, and on the most varied organs of plants, I havenever met with the formation of cells outside cells. Minuteinvestigation in the proper stages of development alwaysshows that the new cells proceed from parent-cells.

Meyen,* indeed, makes a portion of the cellular tissueof the young anther become dissolved, and new cells tooriginate in the homogeneous mucilage. But I haveshown that Meyen mistook a very thin, delicate tissuefor amorphous mucilage, f

Mirbclj considers that the cambium in the root of theDate-palm consists of an amorphous, homogeneous, thickfluid,in which the cells are formed. But in the roots ofthe Date-palm, as in all other cambium in entire sections,I find a continuous cellular tissue, and never any inter-ruption by an amorphous mass.

Schleiden § came to a similar result with regard to thecell-formation in cambium.

Endlicher and Unger || recently affirm cells to originatealso through intercellular formation, appearing first ascavities in the intercellular substance, and acquire properwalls subsequently through the condensation of the latter.But if cells lie in a gelatinous mass, this is by no meansa proof that they have originated in this. The history ofdevelopment must decide whether the cells have beenproduced from the gelatinous mass, or the gelatine fromthe cells. My researches on the Algse and Fungi showto me that, without exception, the cells exist first., andthe gelatinous matter which subsequently surrounds themis produced by the cells. In the simple plants, such asNostoc, Palmella, &c., the development may be tracedfrom the very first cell. In the more complicated plants,

* Physiologie , Band iii, 119; pi. xii, fig. 2.

t Zur Entwickelungsgesch. des Pollens , p. 10, figs. 2-7, 31-36, 47, 48.

+ Nouvelles notes sur le Cambium; Arcliiv de Museum, tome i, pi. xxi.

§ Grundziige d. wiss Bot. 1st Ed. vol. i, p. 199.

]| Grundz. der Botanik, p. 33.