A division by fission followed by Endogenous spore formation, characteristic of the Schizosaccharomycetes.
The non-sexua 1 reproduction takes the form of fission, budding or sporogony, the details of which are described below.
In this way we may distinguish, first, vegetative reproduction, the result of discontinuous growth of the tissues and cell-layers of the body as a whole, leading to (I) fission, (2) autotomy, or (3) vegetative budding; secondly, germinal reproduction, the result of the reproductive activity of the archaeocytes or germinal tissue.
(I) True fission or longitudinal division of an individual into two equal and similar daughter-individuals is not common but occurs in Gastroblasta, where it has been described in detail by Arnold Lang .
(2) Autotomy, sometimes termed transverse fission, is the name given to a process of unequal fission in which a portion of the body separates off with subsequent regeneration.
A " stolon " of unknown origin produces thirty-two buds, which become as many Polypodia; each has twenty-four tentacles and divides by fission repeated twice into four individuals, each with six tentacles.
In some Syllids this posterior region separates off from the rest, producing a new head; thus a process of fission occurs which has been termed schizogamy.
The perfecting of the microscope led to a full comprehension of the great doctrine of cell-structure and the establishment of the facts - (r) that all organisms are either, single corpuscles (so-called cells) of living material (microscopic animalcules, &c.) or are built up of an immense number of such units; (2) that all organisms begin their individual existence as a single unit or corpuscle of living substance, which multiplies by binary fission, the products growing in size and multiplying similarly by binary fission; and (3) that the life of a multicellular organism is the sum of the activities of the corpuscular units of which it consists, and that the processes of life must be studied in and their explanation obtained from an understanding of the chemical and physical changes which go on in each.
But it was only after Darwin that the cell-theory of Schwann was extended to the embryology of the animal kingdom generally, and that the knowledge of the development of an animal became a knowledge of the way in which the millions of cells of which its body is composed take their origin by fission from a smaller number of cells, and these at last from the single egg-cell.
The ovicells are modified zooecia, and contain numerous embryos which in the cases so far investigated arise by fission of a primary embryo developed from an egg.
In the Phylactolaemata, however, a new colony may originate not only from a larva, but also from a peculiar form of bud known as a statoblast, or by the fission of a fully-developed colony.
In the Cyclostomata the primary embryo undergoes repeated fission without developing definite organs, and each of the numerous pieces so formed becomes a free larva, which possesses no alimentary canal.
Under these conditions the lactose decomposes into dark-brown fission products, the fat loses its emulsified condition and separates out as cream which cannot be made to diffuse again even by shaking, and the albuminoids are converted into a form very difficult of digestion.
All Trypanosomes are capable of binary longitudinal fission, and this appears to be the chief method of multiplication.
Equiperdum) the longitudinal fission is apparently multiple, three or even four descendants being produced simultaneously.
- Stages in Binary Longitudinal Fission of Trypanosoma brucei.
These young individuals can themselves multiply by equal binary fission, giving Anterior flagellum; Posterior flagellum; Longitudinal striations nemes); Cytoplasmic vacuole.
The parasites multiply in two ways - (a) by binary fission, and (b) by multiple division or segmentation.
A, Typical pear-shaped or oval forms; b, various stages in longitudinal division; c, nuclear division preparatory to multiple fission; d, endoglobular forms, in red blood-corpuscles (p = pigment grains); e, bacillary form of the parasite in a corpuscle; M, large macrophageal cell with many parasites (after Donovan).
A, Ordinary forms of varying sizes; b c, stages in multiple division; d, binary fission; e, f, g, flagellate forms (after Rogers).
B, a specimen undergoing fission (X 20).
It is further stated by Olive that the chromosomes undergo longitudinal fission, and that for the same species the same number of chromosomes appear at each division.
This theory of the genesis of double-stars by fission is not, however, universally accepted; in particular objections have been urged by T.
Sooner or later, however, the scyphistoma produces free medusae by a process of transverse fission termed strobilization.
We haven't even begun to figure out all the ways we might get unlimited free and clean power from nuclear fission or fusion or other ways to unlock the vast power stored in the atom.