224 METAMORPHOSIS OF TISSUE. 



metaphosphates which it contains, &c., it becomes highly pro- 

 bable that the contents of the blood-corpuscles have either an 

 actually acid reaction, or that, analogously with the yolk-fluid, they 

 contain substances which are able to saturate the alkalies. 



When we consider all that has been ascertained in reference to 

 the nature of the free acids in the different animal juices, and all 

 that has been set forth in different parts of the present work, we 

 find that wherever free acids occur in the parenchyma of the organs 

 acid phosphates are invariably present, or that where an acid re- 

 action cannot be directly recognised, phosphoric acid is always met 

 with, either conjugated or simply combined with casein, globulin, 

 or glycerine. The proposition may, therefore, be established for 

 all animal juices, which are neither secretions nor excretions, that in 

 all juices which exhibit an acid reaction the soluble phosphates are 

 especially accumulated, for it has been found that whenever the 

 mineral constituents were determined by the ordinary method of in- 

 cineration, the ash of all these juices, whether they exhibited an acid 

 or a neutral reaction, was much richer in phosphates, and espe- 

 cially metaphosphates, than the ash of alkaline animal juices. As 

 all these juices naturally originate in the blood, it would appear 

 very singular, although by no means incomprehensible, that cer- 

 tain of these juices, as for instance the muscular juice, arid the 

 fluid bathing the contractile fibres, should exhibit such a strongly 

 acid reaction if free organic acids and their alkaline salts were rot 

 also simultaneously present with the acid phosphates. This free acid, 

 which as we have already seen, consists essentially of lactic acid, to- 

 gether with a smaller quantity of volatile organic acids, is originally- 

 generated in the parenchyma of the organs by their own functions, 

 and the neutral phosphate which has passed from the blood is here 

 first converted into an acid phosphate ; such at all events is the 

 case with the muscles, which Du Bois found to be without free 

 acids when in a state of rest. We are, therefore, disposed to adopt 

 the view advanced by Berzelius many years since, that this acid 

 reaction is not the requirement, but the result of the function of 

 the muscles. 



Moreover the earthy phosphates are also brought into solution 

 in larger quantity by the occurrence of free acids, than would have 

 been the case by albumen or casein alone. It need not, therefore, 

 excite our surprise, if we find large quantities of these phosphates 

 present in the ash of the animal juices, for such a fact would at 

 first sight appear to be the mere result of a chemical necessity ; 

 but we have already shown that although no free organic acids are 

 formed anew in the parenchyma of the organs, the occurrence of 



