4.  Cell-division with rejuvenescence forms the spores of mosses and higher cryptogams.

To take the example of moss spores: 

Certain cells in the sporogonium of a moss are called mother-cells.  The protoplasm of each one of these becomes divided into four parts.  Each of these parts then secretes a cell-wall and becomes free as a spore by the rupture or absorption of the wall of the mother-cell.  The germination of the spores I shall describe later.

5.  A process of budding which in the yeast plant and in mosses is merely vegetatively reproductive, in fungi becomes truly reproductive, namely, the buds are special cells arising from other special cells of the hyphae.

For example, the so-called “gills” of the common mushroom have their surface composed of the ends of the threads of cells constituting the hyphae.  Some of these terminal cells push out a little finger of protoplasm, which swells, thickens its wall, and becomes detached from the mother-cell as a spore, here called specially a basidiospore.

Also in the common gray mould of infusions and preserves, Penicillium, by a process which is perhaps intermediate between budding and cell-division, a cell at the end of a hypha constricts itself in several places, and the constricted portions become separate as conidiospores.

Teleutospores, uredospores, etc., are other names for spores similarly formed.

These conidiospores sometimes at once develop hyphae, and sometimes, as in the case of the potato fungus, they turn out their contents as a swarm-spore, which actively moves about and penetrates the potato leaves through the stomata before they come to rest and elongate into the hyphal form.

So far for asexual methods of reproduction.

I shall now consider the sexual methods.

The distinctive character of these methods is that the cell from which the new individual is derived is incapable of producing by division or otherwise that new individual without the aid of the protoplasm of another cell.

Why this should be we do not know; all that we can do is to guess that there is some physical or chemical want which is only supplied through the union of the two protoplasmic masses.  The process is of benefit to the species to which the individuals belong, since it gives it a greater vigor and adaptability to varying conditions, for the separate peculiarities of two individuals due to climatic or other conditions are in the new generation combined in one individual.

The simplest of the sexual processes is conjugation.  Here the two combining cells are apparently of precisely similar nature and structure.  I say apparently, because if they are really alike it is difficult to see what is gained by the union.