14 S. E. Henschen, 



intention of finding out where the arsenic appears in largest percentage 

 after poisoning, others made a microscopical examination of these parts. 



The first method must already a priori be acknowledged as rather 

 untrustworthy since no proof was forthcoming that the parts of the nerve 

 system retaining the greatest percentage of arsenic were also most af- 

 fected. This way was however accepted by Scolozouboff^) who came to 

 the result that a greater percentage of arsenic was found in the brain 

 and spinal cord than in the muscles and consequently drew the conclu- 

 sion that arsenic paralysis depends upon changes in the spinal cord since 

 no clinical symptoms show that the brain is the seat of the disease. 



This inference however can still less be regarded* as correct be- 

 cause other inquirers such as Ludwig etc. on analyzing, came to a con- 

 trary conclusion, namely that the muscles contain comparativel}^ more 

 arsenic than the central nervous system. 



More important were the pathological anatomical experimental 

 investigations. Vulpian^) was on account of an examination of the spinal 

 cord of an arsenic poisoned rabbit inclined to localize arsenic paralysis 

 to the spinal cord but considered his conclusions uncertain because of 

 the ill preserved condition of the latter. 



Through his poisoning experiments on dogs Popow^) came to the 

 identical result that paralysis depends upon acute diffuse myelitis. He 

 found besides changes in the vessels, hemorrhage in the grey substance, 

 certain changes in the cells, the protoplasm of the latter being clouded, 

 cell body rounded, nucleus scarcely noticeable, and the processes shorter 

 than normal. Besides these in the cells pigmentation and formation of 

 vacuoles were found. More over, even in the white substance changes 

 appeared such as tliickening of the axis cylinders: on the other hand 

 Popow could not verify the changes in the peripheral nerves. 



In the meanwhile Kreyssig*) came with his experiments (which 

 were intended to control Popow's investigations), to the conclusions that 

 those changes distinguished by Popow were either artificial or could be 

 found under normal conditions. Also Kreyssig found hemorrhages in 

 the spinal cord, although only microscopical in size. 



1) Arch, de physiol. normal et. patliol. 1884 P. 323. 



2) Leçons sur les malad, nerv 1879. 



3) Virchow Arch. Bd. 93. 



4) Vh-chows Arch. 102. 



