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Show 88 PARTICULAR CONSIDER AT IONS ON THE Now the chemist, by the association of .two parts (Jxygen, four hydrogen, two carbon, and two nitro.ge~, can make urea. Alantoin has also been produced a;tlfic1ally. Two of the proximate principles bejng real.Izable ~y human care, the possibility of realizing or for~1ung all 1~s ~sta~lished. Thus the chemist may be said to have 1t In his power to realize the .first step in organization .. * Indeed, it is fully acknowledged by J?r. Daub~ny? that 1n the ~omuinations forming the proximate prinCiples there lS no chemical peculiarity. "It is no~ ~ertain," he says, "that the same simple laws of comp~sihon p~rvade the whole creation; and that, if the organic c~em.Ist onl~ tak~s the requisite precautions to avoid resol vmg Into t~eu ulumate elements the proximate principles upon w h1ch he operates the results of his analysis will show that they are combined precisely according to the same plan as t~e elements of mineral bodies are known to be.''t A pa~ticular fact is here worthy of attention. "The conversiOn of fecula into sugar, as one of the ordinary ~rocesses ot vegetable economy, is effec~ed by th~ production of a secretion termed diastose which occasions both the rupture of the starch vesicles, a'nd the change of their conta~ned gum into sugar. This diastase may be separa~ely obtained by the chemist, and it acts as effectually m h1s !a~orato.ry as in the vegetable org-anization. He can als~ Imitate Its effects by other chemical agents."+ The wnter quoted · · below adds, h No reasonable ground has yet b~e~ adduced for supposing that, if we had the power of br~nging .together the eJements of any organic compound, In theu requisite states and proportions, .the re~u)t would }e any other than that whiCh is found In the living b~dy. . It is much to know the elements out of which organ~c bodies are composed. It is somethi~g more to k.now theu first combinations and that these are sun ply chemical. H?w these combinations are associated in the structure of living bodies is the next inquiry, but .it is one to _whic~ as yet no satisfactory answer c~n be given. The I_nvestigation of the minutim of organic structure by the microscope .,. Fatty matter has also been formed in the laboratory. The pro cess co nsi ted in passing a mixture of carbonic ~cid, p:ue h Y drog~ n and carburetted hydrogen in the pro~;>orhon. o1 one ~1easure oft e tfuirhste,. twenty of the second, and ten of the th1rd, thro~gh a red-hot t Supplement to the Atomic Theory. . . t Carpenter on LiCe j Todd's Cyclop~d1a of PhysiOlogy. ORIGIN OF THE ANIMATED TRIBES. is of such recent origin, that its results cannot be expected to be very clear. Some facts however, are worthy of attention with regard to the present inqui1·y. It is ascertained that the basis of all vegetable and animal substances consists of nucleated cells; that is, cells having granules within them. Nutriment is converted into these before being assimilated by the system. The tissues are forrned ii·om them. The ovum destined to becomr a new creature, is originally only a cell with a contained granule We see it acting this reproductive part in the simplest manner in the cryptogamic plants. " The parent cell arrived at maturity by the exercise of its organic functions, bursts, and liberates its contained granules. These, at once thrown upon their own resources, and entirely dependent for their nutrition on the surrounding elements, develope themselves into new cells, which repeat the life of their original. Amongst the l1igher tribes of the cryptogamb, the reproductive cell does not burst, but the first cells ofthe new structure are developed within it, and these gradually extend, by a similar process of multiplication, into that primary leaf-like expansion which is the fil'st formed structure in all plants."* I-fere the little cell becomes di1 ·ectly a plant, the /ull-fm·med living body. H is also worthy of remark that, in the sponges, (an animal form,) a gemmule detached from the body of the parent, and trusting for sustentation only to the fluid into which it has been cast, becomes, without further process, the new creature. Farther, it has been recently discovered by means of the microscope, that there is, as far as can be judged, a perfect resemblance between the ovum of the mammal tribes during that early stage when it is passing through the oviduct, and the young of the infusory animalcules. One of the most remarkable of thes8, the ·vol- SJ vo.:<: gtobator, has exactly the form of the germ which af-ter passing through a long fee tal progress becomes a comr, tete mammifer, an animal of the highest class. It has even been found that both are alike p'l'ovided with those cilia, :Which, producing a revolving motion, or its appear. ance, 1s partly the cause of the name given to this animalcule. These resemblances a:·e the more entitled to notice, that they were made by various observers, distant from • Carpenter's Report on the Result• obtained by the :ldicroscopa in the Study of Anatomy and Physiology, 1843. 8 |