{166} “A glass tube is to be bent into a syphon, and placed with the curve downwards, and in the bend is to be placed a small portion of mercury, not sufficient to close the connexion between the two legs; a solution of nitrate of silver is then to be introduced until it rises in both limbs of the tube. The precipitation of the mercury, in the form of an Arbor Dianæ, will then take place, slowly, only when the syphon is placed in a plane perpendicular to the magnetic meridian; but if it be placed in a plane coinciding with the magnetic meridian, the action is rapid, and the crystallization particularly beautiful, taking place principally in that branch of the syphon towards the north. If the syphon be placed in a plane perpendicular to the magnetic meridian, and a strong magnet brought near it, the precipitation will commence in a short time, and be most copious in the branch of the syphon nearest to the south pole of the magnet.” {169a} Fatty matter has also been formed in the laboratory. The process consisted in passing a mixture of carbonic acid, pure hydrogen, and carburetted hydrogen, in the proportion of one measure of the first, twenty of the second, and ten of the third, through a red-hot tube. {169b} Supplement to the Atomic Theory. {170} Carpenter on Life; Todd’s Cyclopædia of Physiology. {171} Carpenter’s Report on the results obtained by the Microscope in the Study of Anatomy and Physiology, 1843. {172} See Dr. Martin Barry on Fissiparous Generation; Jameson’s Journal, Oct. 1843. Appearances precisely similar have been detected in the germs of the crustacea. {175} Mr. Leonard Horner and Sir David Brewster, on a substance resembling shell.—_Philosophical Transactions_, 1836. {179a} Dr. Allen Thomson, in the article _Generation_, in Todd’s Cyclopædia of Anatomy and Physiology. {179b} The term aboriginal is here suggested, as more correct than spontaneous, the one hitherto generally used. {182} Article “Zoophytes,” Encyclopædia Britannica, 7th edition. {187} See a pamphlet circulated by Mr. Weekes, in 1842. {195} Daubenton established the rule, that all the viviparous quadrupeds have seven vertebræ in the neck. {201} Lord’s Popular Physiology. It is to Tiedemann that we chiefly owe these curious observations; but ground was first broken in this branch of physiological science by Dr. John Hunter. {204} When I formed this idea, I was not aware of one which seems faintly to foreshadow it—namely, Socrates’s doctrine, afterwards dilated on by Plato, that “previous to the existence of the world, and beyond its present limits, there existed certain archetypes, the embodiment (if we may use such a word) of general ideas; and that these archetypes were models, in imitation of which all particular beings were created.” {208} The numbers 1, 3, 6, 10, 15, 21, 28, &c. are formed by adding the successive terms of the series of natural numbers thus: