Professor Yaeger's theory explains further to us that other great mystery of Nature--the transmission from parent to offspring of the morphological speciality. This is another puzzle of the biologist. What is there in the embryonal germ that evolves out of the materials stored up therein a frame similar to the parents? In other words, what is there that presides over the preservation of the species, working out the miniature duplicate of the parents' configuration and character? It is the protoplasm, no doubt; and the female ovum contains protoplasm in abundance. But neither the physicist nor the chemist can detect any difference between the primordial germ, say of the fowl, and that of a female of the human race. In answer to this question--a question before which science stands perplexed--we need only remember what has been said before about the protoplasmic scent. We have spoken before of the specific scent of the animal as a whole. We know, however, that every organ and tissue in a given animal has again its peculiar scent and taste. The scent and taste of the liver, spleen, brain, &c., are quite different in the same animal. And if our theory is correct, then it could not be otherwise. Each of these organs is differently constructed, and as variety of organic structure is supposed to be dependent upon variety of scent, there must necessarily be a specific cerebral scent, a specific splenetic scent, a specific hepatic scent, &c. &c. What we call, then, the specific scent of the living animal must, therefore, be considered as the aggregate of all the different scents of its organs. When we see that a weak solution of sulphuric acid is capable of disengaging from the blood the scent of the animal, we shall then bear in mind that this odorous emanation contains particles of all the scents peculiar to each tissue and organ of the animal. When we further say that each organ in a living animal draws by selective affinity from the blood those materials which are necessary for its sustenance, we must not forget that each organ draws at the same time by a similar selective affinity the specific odorous substances requisite for its constructive requirements. We have now only to suppose that the embryonal germ contains, like the blood itself, all the odorous substances pertaining to the various tissues and organs of the parent, and we shall understand which is the moving principle in the germ that evolves an offspring, shaped in the image and after the likeness of the parents. In plants it is the blossom which is entrusted with the function of reproduction, and the odorous emanations accompanying that process are well known. There is strong reason to believe that something similar prevails in the case of animals, as may be seen from an examination of what embryologists call the aura seminalis.