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By this time too it was realized that the formation of cells de novo, postulated by Schleiden’s theory of “phytogenesis,” did not occur.

Schleiden utilized Brown’s discovery, and although his theory of phytogenesis is based on erroneous observations, yet the great importance which he rightly attached to the nucleus as a cell-structure made it possible to extend the cell-theory to animal tissues also.

Phytogenesis, fī-tō-jen′e-sis, n. the theory of the generation of plants—also Phytog′eny.—adjs.

Schwann’s treatise, entitled Microscopical Researches into the Accordance in the Structure and Growths of Animals and Plants, was published in German at Berlin in 1839, and was translated into English by Henry Smith, and printed for the Sydenham Society in 1847, along with a translation of Schleiden’s memoir, “Contributions to Phytogenesis,” which originally appeared in 1838 in M�ller’s Archiv for that year, and which had also been published in English in Taylor and Francis’s Scientific Memoirs, vol. ii. part vi.

He outlined his views in an epochal paper published in Muller's Archives in 1838, under title of "Beitrage zur Phytogenesis."