its entire contents diffused.  To follow with our utmost powers these exquisite specks was an unspeakable pleasure, a group seen to roll from the sac, when nearly empty, were fixed and never left.  They soon palpably changed by apparent swelling or growth, but were perfectly inactive; but at the end of three hours a beaked appearance was presented.  Rapid growth set in, and at the end of another hour, how has entirely baffled us, they acquired flagella and swam freely; in thirty-five minutes more they possessed a nucleus and rapidly developed, until at the end of nine hours after emission a sporule was followed to the parent condition and left in the act of fission.  In this way, with what difficulties I need not weary you, a complete life-cycle was made out.

And now I will invite your attention to the developmental history of the most minute of the six forms we studied.  In form it is a long oval, it is without visible structure or differentiation within, and is possessed of only a single flagellum.  Its utmost length is the 1/5000 of an inch.  Its motion is continuous in a straight line, and not intensely rapid, nor greatly varied, being wholly wanting in curves and dartings.  The copiousness of its increase was, even to our accustomed eyes, remarkable in the extreme, but the reason was discovered with comparative ease.  Its fission was not a division into two, but into many.  The first indication of its approach in following this delicate form was the assumption rapidly of a rounder shape.  Then followed an amoeboid and uncertain form, with an increased intensity of action which lasted a few moments, when lassitude supervened, then perfect stillness of the body, which is now globular in form, while the flagellum feebly lashed, and then fell upon and fused with the substance of the sarcode.  And the result is a solid, flattened, homogeneous ball of living jelly.

To properly study this in its further changes, a power of from three to four thousand diameters must be used, and with this I know of few things in the whole range of minute beauty more beautiful than the effect of what is seen.  In the perfectly motionless flattened sphere, without the shimmer of premonition and with inconceivable suddenness, a white cross smites itself, as it were, through the sarcode.  Then another with equal suddenness at right angles, and while with admiration and amazement one for the first time is realizing the shining radii, an invisible energy seizes the tiny speck, and fixing its center, twists its entire circumference, and endows it with a turbined aspect.  From that moment intense interior activity became manifest.  Now the sarcode was, as it were, kneading its own substance, and again an inner whirling motion was visible, reminding one of the rush of water round the interior of a hollow sphere on its way to a jet or fountain.  Deep fissures or indentations showed themselves all over the sphere; and then at the end of ten or more minutes all interior action ceased,