OBJECTION OF CELL THEORY (REASONS OF DISCARTION)

(i)       Living organism are composed of various types of cells and their product but members of monera & protista don't have a cellular organisation, they have protoplasmic grade & organization.

Cell theory is not applicable on viroids, Viruses, Prions.

(ii)      In multicellular organism one type of cell perform one type of function. It doesn't perform all vital activities.

(iii)         Gene is the hereditary unit of life according to modern view - Physical unit of life = Gene

Chemical unit of life = DNA

(iv)      In plants many dead cells are present, which also have specific function. Vessels and Tracheids of Xylem are dead cells but helps in conduction of water & minerals. In human beings, cells of stratum corneum (outermost layer of skin) are dead & helps in protection.

(v)      It was not discarded but modified by Nageli, he just added "through cell division" while omnis cellula e cellula means that cells arise inside the cell. According to Karl nageli "new syncytes arise from division of pre-existing cells".