COMPOSITION OF TISSUES. 119 



is formed, also, from albumen, which contains only 

 half as much phosphorus as fibrine. 



Every attempt to give the true absolute amount of 

 the atoms in fibrine and albumen in a rational formula, 

 in which the sulphur and phosphorus are taken, not in 

 fractions, but in entire equivalents, must be fruitless, 

 because we are absolutely unable to determine with 

 perfect accuracy the exceedingly minute quantities of 

 sulphur and phosphorus in such compounds ; and be- 

 cause a variation in the sulphur or phosphorus, smaller 

 in extent than the usual limit of errors of observation, 

 will affect the number of atoms of carbon, hydrogen, 

 or oxygen to the extent of 10 atoms or more. 



We must be careful not to deceive ourselves in our 

 expectations of what chemical analysis can do. We 

 know, with certainty, that the numbers representing 

 the relative proportions of the organic elements are the 

 same in albumen and fibrine, and hence we conclude 

 that they have the same composition. This conclusion 

 is not affected by the fact, that we do not know the 

 absolute number of the atoms of their elements, which 

 have united to form the compound atom. 



15. A formula for proteine is nothing more than 

 the nearest and most exact expression in equivalents, 

 of the result of the best analyses ; it is a fact estab- 

 lished so far, free from doubt, and this alone is, for 

 the present, valuable to us. 



If we reflect, that from the albumen and fibrine of 

 the body all the other tissues are derived, it is perfectly 

 clear, that this can only occur in two ways. Either 



