It will be observed that M. Flourens uses language which cannot be mistaken. For him, the labours of Von Baer, of Rathke, of Coste, and their contemporaries and successors in Germany, France, and England, are non-existent: and, as Darwin "_imagina_" natural selection, so Harvey "_imagina_" that doctrine which gives him an even greater claim to the veneration of posterity than his better known discovery of the circulation of the blood. Language such as that we have quoted is, in fact, so preposterous, so utterly incompatible with anything but absolute ignorance of some of the best established facts, that we should have passed it over in silence had it not appeared to afford some clue to M. Flourens' unhesitating, _ à priori_, repudiation of all forms of the doctrine of progressive modification of living beings. He whose mind remains uninfluenced by an acquaintance with the phænomena of development, must indeed lack one of the chief motives towards the endeavour to trace a genetic relation between the different existing forms of life. Those who are ignorant of Geology, find no difficulty in believing that the world was made as it is; and the shepherd, untutored in history, sees no reason to regard the green mounds which indicate the site of a Roman camp as aught but part and parcel of the primæval hillside. So M. Flourens, who believes that embryos are formed "tout d'un coup," naturally finds no difficulty in conceiving that species came into existence in the same way. IV THE GENEALOGY OF ANIMALS [Footnote: _The Natural History of Creation_. By Dr. Ernst Haeckel. [_Natürliche Schöpfungs-Geschichte_.--Von Dr. Ernst Haeckel, Professor an der Universität Jena.] Berlin, 1868.] [1869] Considering that Germany now takes the lead of the world in scientific investigation, and particularly in biology, Mr. Darwin must be well pleased at the rapid spread of his views among some of the ablest and most laborious of German naturalists. Among these, Professor Haeckel, of Jena, is the Coryphæus. I know of no more solid and important contributions to biology in the past seven years than Haeckel's work on the "Radiolaria," and the researches of his distinguished colleague Gegenbaur, in vertebrate anatomy; while in Haeckel's "Generelle Morphologie" there is all the force, suggestiveness, and, what I may term the systematising power, of Oken, without his extravagance. The "Generelle Morphologie" is, in fact, an attempt to put the Doctrine of Evolution, so far as it applies to the living world, into a logical form; and to work out its practical applications to their final results. The work before, us, again, may be said to be an exposition of the "Generelle Morphologie" for an educated public, consisting, as it does, of the substance of a series of lectures delivered before a mixed audience at Jena, in the session 1867-8.