fi90 Dr. Barry's Account of tlie Discoveries of Keber 



into the humours can be no longer seriously doubted. Lastly, 

 the circumstance that, after its application as blue ointment, 

 mercury in the metallic form has been found, not only in many 

 parts of the body, but even in the saliva*, is evidence of a very 

 general porosity of the animal formations. 



To meet these inexorable postulates of logic and experimental 

 proof, science in its present position gives us on this exceedingly 

 important subject no satisfactory disclosure. In vain do we 

 seek in €ompendiums of physics for definite specifications of the 

 size, form, and condition in other respects, of the pores of gold 

 through which, in the experiment above mentioned, water is 

 pressed out, or of the pores of granite through which the latter 

 in water becomes saturated. Still less is modern physiology in 

 a condition to mark with certainty the ways in which those sub- 

 stances get from the surface of the skin into the blood. While, 

 through the united efibrts of the greatest physiologists of the 

 age, we have at length advanced so far as to see laid aside the 

 vice clandestinaf of former days, through which it was sought 

 to explain the passage into the urine of substances introduced 

 into the stomach, suspicion from another side shows itself anew, 

 that the animal membranes, and especially the capillary walls, 

 notwithstanding their undoubtedly closed state, may either 

 everywhere, or at certain parts, possess apertures which have 

 defied the methods of examination hitherto employed, and by 

 which minutely divided solid substances are let through. 



But the permeability of organic membranes for gases and 

 fluid substances also, has nothing in modern science to support 

 it besides the grounds of induction, it having hitherto with 

 certainty been optically demonstrated by none. In proof of 

 the correctness of these assertions, I refer to what has been 

 enunciated by some of the greatest authorities now living ; for 

 instance, by a Johannes MiillerJ, Valentin§, R. Wagner||, 

 Henle^, Liebig**, and others, from whose accordant evidence it 

 follows, that the permeability of animal membranes for gases, 

 liquids, and even under particular circumstances for finely 

 divided solid bodies, is in physiology an established fact, yet 



* In the saliva of a child in scarlatina, treated with blue mercurial 

 ointment on accoimt of swelling of glands of the neck, single globules of 

 mercury, having a diameter of ^xyW"> were, as moderate sahvation ap- 

 peared, also noticed by myself. 



t See J. MiiUer, Handb. der Physiol, des Mencken, vol. i. 1844, p. 1.97. 



j Handbach der Physiologie des Menschen, vol. i. 1844, pp. 193, 194. 



§ Lehrbuch der Physiologie des Menschen, vol. i. 1844, p. 63. 



II Lehrbuch der Speciellen Physiologie, '2nd edit., 1843, p. 206, § 171, 

 note 2. 



If Rationelle Pathologic, vol. ii. 1847, p. 145. 



•* Untersuchungen iiber einige Ursachen der SUftebewegung, 1848, p. 4. 



