the result of my life’s work.  I have devoted my whole life to the study of Nature, and yet a single sentence may express all that I have done.  I have shown that there is a correspondence between the succession of Fishes in geological times and the different stages of their growth in the egg,—­this is all.  It chanced to be a result that was found to apply to other groups and has led to other conclusions of a like nature.  But, such as it is, it has been reached by this system of comparison, which, though I speak of it now in its application to the study of Natural History, is equally important in every other branch of knowledge.  By the same process the most mature results of scientific research in Philology, in Ethnology, and in Physical Science are reached.  And let me say that the community should foster the purely intellectual efforts of scientific men as carefully as they do their elementary schools and their practical institutions, generally considered so much more useful and important to the public.  For from what other source shall we derive the higher results that are gradually woven into the practical resources of our life, except from the researches of those very men who study science not for its uses, but for its truth?  It is this that gives it its noblest interest:  it must be for truth’s sake, and not even for the sake of its usefulness to humanity, that the scientific man studies Nature.  The application of science to the useful arts requires other abilities, other qualities, other tools than his; and therefore I say that the man of science who follows his studies into their practical application is false to his calling.  The practical man stands ever ready to take up the work where the scientific man leaves it, and to adapt it to the material wants and uses of daily life.

The publication of Cuvier’s proposition, that the animal kingdom is built on four plans, created an extraordinary excitement throughout the scientific world.  All naturalists proceeded to test it, and many soon recognized in it a great scientific truth,—­while others, who thought more of making themselves prominent than of advancing science, proposed poor amendments, that were sure to be rejected on farther investigation.  There were, however, some of these criticisms and additions that were truly improvements, and touched upon points overlooked by Cuvier.  Blainville, especially, took up the element of form among animals,—­whether divided on two sides, whether radiated, whether irregular, etc.  He, however, made the mistake of giving very elaborate names to animals already known under simpler ones.  Why, for instance, call all animals with parts radiating in every direction Actinomorpha or Actinozoaria, when they had received the significant name of Radiates?  It seemed, to be a new system, when in fact it was only a new name.  Ehrenberg, likewise, made an important distinction, when he united the animals according to the difference in their nervous systems; but he also incumbered the nomenclature unnecessarily, when he added to the names Anaima and Enaima of Aristotle those of Myeloneura and Ganglioneura.