METAMORPHOSIS OF TISSUE. 



required to supply the first basis for the new tissue, even in the 

 case of those organs which subsequently exhibit an excess of car- 

 bonate of lime. After considering all these facts, we can scarcely 

 entertain a doubt of the positive influence which the phosphates 

 exert on the formation of the tissues and organs. The effects and 

 counteractions reciprocally induced by the phosphates and organic 

 matters in the development of the tissues and in their maintenance, 

 are subjects which still require elucidation. If any doubt still 

 exist as to the share taken by the phosphates in the formation and 

 functions of certain tissues, the observation made by Liebig, must 

 we think, finally set them at rest ; we refer to the fact noticed by 

 that observer, that herbivorous animals take up a very small quan- 

 tity of phosphates in their food, and although their blood is very 

 poor in those substances, their tissues and organs contain as large 

 a proportion of these salts as the corresponding parts of the carni- 

 vora. The phosphates must, therefore, be especially attracted and 

 retained by the tissues in the organism of the herbivora, in order 

 that they may there fulfil definite effects corresponding to the 

 objects of the several organs, which could not be fulfilled by the 

 other substances which are supplied in abundant quantities in the 

 vegetable food of these animals. The very variable amount of 

 these salts which we meet with in the blood of herbivorous 

 as well as carnivorous animals, and which obviously depends only 

 upon the nature of the food, or, in other words, upon the quantity 

 of phosphoric acid which it contains, led Liebig to adopt the view 

 that the phosphates do not exert any perceptible influence upon 

 the process of the formation or the main functions of the blood, 

 that is to say, upon nutrition and the development of heat. The 

 facts we have already considered, and those which still demand our 

 notice, coincide so fully with Liebig's view, that future investiga- 

 tions are not likely to modify it. We shall revert at the proper 

 place to the relations of the phosphates in secretion, excretion, and 

 similar processes. 



The alkali and the carbonates predominate in the liquor san- 

 guinis (serum + fibrin), in the same manner as the free acid and 

 phosphates in the fluids of the tissues. We have seen that the 

 alkalinity of the liquor sanguinis is not induced by the free alkali, 

 but by certain saline compounds of alkalies, and more especially 

 of soda with albuminous substances on the one hand, and with 

 carbonic acid, and in part also with phosphoric acid, on the other 

 hand. The albumen of the blood-serum is combined with soda in 

 at least a two-fold proportion, constituting an acid and neutral, or 



