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EEV. PROF. G. HENSLOWj M.A., F.L.S.^ 



Sir A. H. Church only applied his term to the manufacture 

 of some definite organic products, as indigo, madder, some 

 sugars, etc, but it covers really the whole field of the entire 

 structure of animals and plants, and when these change under 

 changed conditions of life, it lies at the root of Evolution itself. 

 Every cell implies a "purpose," which the elements C,H,0, 

 combined to form " cellulose " could never per se accomplish, 

 and when the organs of an animal or plant change, to become 

 adapted to new uses under new conditions, nothing but 

 directivity could effect the alteration. Thus paws of some 

 terrestrial quadrupeds became paddles in whales, seals, and 

 other marine mammalia ; non-sensitive leaves and normally 

 flowering branches have become tendrils sensitive to the 

 slightest touch to enable them to be used as climbing 

 organs. 



Nothing of the sort or any adaptations exist in the mineral 

 kingdom, though certain kinds of constant directivities prevail ; 

 thus, not only gravity but the planets' motions are expressible 

 by mathematical formula'. The forms of crystals are constant 

 so far as the angles between their facets are concerned. 

 Cliemical combinations of elements are made according to fixed 

 laws and in all cases matter moves under strictly directed forces ; 

 but they never change. 



Now let us turn to the organic world. Animals and plants 

 grow by means of food. This is a mixture of matter and force 

 or energy. In the case of animals, it reaches nature's internal 

 laboratory, where, just as a chemist mixes various substances in 

 his laboratory, ferments, bile, acids, alkalies, etc., are severally 

 supplied by secreting organs as required. The result is blood. 

 Leaving the chemical dej)artmient, this is now ready for distribu- 

 tion by means of the action of the engine or heart, which transmits 

 it to every, the minutest part of the body ; for if one pricks 

 any spot with the finest needle, blood is sure to come out. "We 

 might compare the circulation of the blood to a train leaving 

 a terminus, laden with all sorts of parcels directed to various 

 stations along the line, which the train deposits on arriving at 

 them respectively. Just so is it with the blood, for lime is 

 deposited in larger quantity where bones are forming, as well 

 as to the teeth. Silica or flint is conveyed to the teeth, nails 

 and hair. The scarce mineral fluor — which is the material made 

 into vases and ornaments of purple, yellow, and other colours 

 in Derbyshire, known as " Blue John " or Fluorspar — is found 

 located in the enamel of the teeth. Salt reaches the tears but 

 does not stop at the mouth. Phosphorus is an important 



