lODUM. 113 



avoided in practice ; and, as far as we know, less degrees of 

 the same cannot be usefully applied to therapeutical purposes, 

 unless the tendency to coagulation of the blood be somewhat 

 increased by it. 



3. SPECIFIC ACTION AND USES. 



The iodide of sodium and albuminous compounds pass from 

 the blood into the tissues with remarkable rapidity, and may be 

 found in all of them, especially the excreting organs and 

 lymphatic glands, whilst they appear very scantily in the 

 nervous centres. Almost as quickly the iodine leaves the 

 tissues ; and in thus passing rapidly through the protoplasm of 

 the body, and sharing in its metabolism by combining (probably 

 very loosely) with the albuminous molecules, it no doubt 

 accelerates tissue change. As no increase of urea accompanies 

 this effect, nor bodily wasting, the iodine must either spare the 

 liver (which is the chief source of urea), or accelerate the meta- 

 bolism of the plasma, rather than of the tissue elements them- 

 selves. (See Metabolism, Part III.) However this may be, the 

 following are the principal directions in which iodine affects 

 nutrition, and their applications : 



(1) The lymphatic glands are reduced in size by iodine, 

 which is extensively used for scrofulous and other chronic 

 enlargements of the glands, whether applied locally as iodine, 

 or internally as the iodides. 



(2) Certain poisons, which have intimately associated them- 

 selves with the albuminous structures, are disengaged from this 

 combination by iodine. Lead and mercury may be swept out 

 of the tissues by iodide of potassium administered for plumbism 

 and hydrargyrism respectively. The principal application, 

 however, of iodine is in the treatment of syphilis. Either the 

 poison of this disease is thus eliminated from the system, or 

 iodine hastens the life and disappearance of the small-celled 

 growth by which syphilis is characterised. It is specially 

 valuable in the tertiary forms of syphilis, when mercury cannot 

 be longer given with advantage ; and nodes and other super- 

 ficial enlargements, gummata in the viscera, and certain forms 

 of skin disease may be very successfully treated by the potas- 

 sium salt. The same precautions must be observed with respect 

 to the general health, and especially the preservation of diges- 

 tion in a course of iodide, as were laid down under the 

 head of mercury. 



(3) In subacute and chronic inflammations of various kinds, 

 such as exudations or effusions in connection with the joints 

 and serous cavities, and some forms of pulmonary consolidation, 

 iodide of potassium may promote absorption by stimulating the 



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