on the Formation of Organic Structure. 191 



informed how it takes place, and particularly whether there 

 be any similar process or instance, in the whole range of ani- 

 mated nature, with which it can be compared?" 



Mr. Main cannot surely be ignorant that the whole solid 

 matter which, during their growth, is added to the bodies of 

 animals, is secreted from their fluid blood ; and that, when 

 a bone is broken, or a part of it taken away, in any animal 

 in a healthy state, the necessary amount of specific matter 

 to repair the injury done is secreted and deposited where 

 wanted. Had Mr. Main consulted the works of many emi- 

 nent physiologists of Germany and France, and, indeed, of 

 every part of the world, he, perhaps, would have been con- 

 vinced that they do not contain a single sentence expressive 

 of a doubt that the true sap of plants possesses, relatively to 

 the functions of vegetable life, powers very closely analogous 

 to those of the blood of animals. 



Perhaps he might object, that the red blood of animals is a 

 heavy compound fluid, abounding with coagulable matters. 

 Agreed. But what then ? Does not blood, in its fluid state, 

 afford another example of the conversion of the hardest and 

 most intractable substances, as grain, bone, cartilage, muscle, 

 &c., into a liquid ? But again ; what has colour to do with the 

 question? The circulating fluid is white, or devoid of tint, 

 in some species, and yet retains the name of blood. The 

 absence or presence of colour will not destroy the analogy ; 

 since the proper juice of plants varies, in that particular, 

 more than the blood does. Fishes have red blood; yet they 

 float in an aqueous medium, which contains no colouring or 

 coagulable material. But some fishes devour their fellows. 

 True. This fact can, however, be scarcely brought for- 

 ward in the instance of fish kept for months and years in a 

 glass globe, and supported by repeated additions of fresh 

 and pure water only. 



Mr. Main has asked, how such and such effects can be 

 produced ; how the process of accretion takes place ? The 

 answer is obvious : they originate in vital action and the 

 chemical powers of life, whose modes of operation are placed 

 beyond the range of human investigation. 



We witness these effects; so we do those of millions of 

 astounding natural phenomena. Thus, the solar rays strike 

 the earth ; heat is evolved ; evaporation is occasioned ; clouds 

 are formed ; and the solar light, that had been absorbed and 

 masked (not quenched) within the earth's surface, and amidst 

 the congregated volume of vapours, keeping their atoms 

 apart and in a state of repulsion, is suddenly reproduced, 

 revealed in flashes of ethereal fire ; while deluges of rain sue- 



