The first change in the yolk, after the formation of the Purkinjean vesicle, is the appearance of minute dots near the wall at the side opposite the vesicle.  These increase in number and size, but remain always on that half of the yolk, leaving the other half of the globe clear.  One can hardly conceive the beauty of the egg as seen through the microscope at this period of its growth, when the whole yolk is divided, with the dark granules on one side, while the other side, where the transparent halo of the vesicle is seen, is brilliant with light.  With the growth of the egg these granules enlarge, become more distinct, and under the microscope some of them appear to be hollow.  They are not round in form, but rather irregular, and under the effect of light they are exceedingly brilliant.  Presently, instead of being scattered equally over the space they occupy, they form clusters,—­constellations, as it were,—­and between these clusters are clear spaces, produced by the separation of the albumen from the oil.

At this period of its growth there is a wonderful resemblance between the appearance of the egg, as seen under the microscope, and the firmament with the celestial bodies.  The little clusters or constellations are unequally divided:  here and there they are two and two like double stars, or sometimes in threes or fives, or in sevens, recalling the Pleiades, and the clear albuminous tracks between are like the empty spaces separating the stars.

This is no fanciful simile:  it is simply true that such is the actual appearance of the yolk at this time; and the idea cannot but suggest itself to the mind, that the thoughts which have been at work in the universe are collected and repeated here within this little egg, which offers us a miniature diagram of the firmament.  This is one of the first changes of the yolk, ending by forming regular clusters with a sort of net-work of albumen between, and then this phase of the growth is complete.

Now the clusters of the yolk separate, and next the albumen in its turn concentrates into clusters, and the dark bodies, which have been till now the striking points, give way to the lighter spheres of albumen between which the clusters are scattered.  Presently the whole becomes redissolved:  these stages of the growth being completed, this little system of worlds is melted, as it were:  but while it undergoes this process, the albuminous spheres, after being dissolved, arrange themselves in concentric rings, alternating with rings of granules, around the Purkinjean vesicle.  At this time we are again reminded of Saturn and its rings, which seems to have its counterpart here.  These rings disappear, and now once more out of the yolk mass loom up little dots as minute as before; but they are round instead of angular, and those nearest the Purkinjean vesicle are smaller and clearer, containing less of oil than the larger and darker ones on the opposite side.  From this time the yolk begins to take its color, the oily cells assuming a yellow tint, while the albuminous cells near the vesicle become whiter.