EXTRACT XX. 



ON METALLIC, OR ARSENIC, AND LEAD, ETC., POISON- 

 ING, AS SEEN ALONG THE LINES DICTATED BY 

 THE FOREGOING VIEWS. 



WE think we see here the lines along which we can most 

 successfully pursue our observations of this momentous 

 problem if we are to arrive at a scientific explanation of 

 the presence of arsenic and lead in such unusual but 

 specific situations as the shafts of the hair and the extensor 

 muscles of the fore-arms respectively. 



The discovery of arsenic in the hair or other parts of 

 a person who has imbibed it medicinally or otherwise 

 through the walls of the alimentary canal, points to its 

 absorption through these walls by the blood vessels or 

 lacteals, its conveyance thence to the neuroglial matrix 

 along with the nerve nutrient elements with which it is 

 imbibed and conveyed to the nerve terminal areas by 

 which the implicated hair and other parts are innervated, 

 or to its exudation with the elements of the cerebro-spinal 

 fluid from the pia mater, and its distribution by that circu- 

 lation to the parts affected, or to its direct absorption or 

 passage from the blood vessels supplying them. The first 

 of these views we prefer to believe as being most in 

 accordance with the teaching of the acknowledged affinity 

 of nerve structures for arsenic and other inorganic poisons ; 

 in which case the poisonous agents must first be supplied 

 to the affected nerve structures, and thence, by histological 

 continuity, to the hairs and other parts by being deposited 

 from the blood of the pia mater in the neuroglial matrix 

 or blastema. 



