more than from 1/20 to 1/10 of a line, or from 1/240 to 1/120 of an
inch, in diameter.

[Illustration: Fig. 1.

_A_. Human Spermatozoön magnified about 3,800 diameters.
_B_. Vertical and lateral views of spermatozoa of man.
_C, D, E, F._ Development of spermatozoa within the vesicles of evolution.
_G_. Cell of the sponge resembling a spermatozoön.
_H_. Vesicles of evolution from the seminal fluid of the dog in the parent cell
_I_. Single vesicles of different sizes.
_J_. Human spermatozoön forming in its cell.
_K_. Rupture of the cell and escape of the spermatozoön.
]

The sperm and the germ-cells contain the primary elements of all organic
structures, and both possess the special qualities and conditions by
which they may evolve organic beings. Every cell is composed of minute
grains, within which vital action takes place. The interior of a cell
consists of growing matter; the exterior, of matter which has assumed
its form and is less active.

When the vital principle is communicated to it, the cell undergoes a
rapid transformation. While this alteration takes place within the cell,
deteriorating changes occur in the cell-wall. Although vital operations
build up these structures, yet the animal and nervous functions are
continually disintegrating, or wasting, them.

Throughout the animal kingdom, germ-cells present the same external
aspect when carefully examined with the microscope. No difference can be