150 Journal of Comparative Neurology. 



ably have a certain number about their bases or active pole. 

 They present a great variety of stages between the full, plump 

 nuclei which have recently reached the cell and the dark, shriv- 

 eled, exhausted cells which seem to have yielded their nourish- 

 ment to the nerve cell. Whether as cause or effect, the condi- 

 tion of general paralysis is accompanied by an abnormal 

 collection of leucocytes. These gather in great numbers in the 

 space between the intima and adventiva of the vascular walls 

 and thus narrow the lumen until a partial stasis of the red cor- 

 puscles results. Masses of yellow pigment accumulate in the 

 adventitious sheath among the the leucocytes, sometimes in con- 

 siderable quantities. These haematoid granules have been 

 frequently noticed. This yellow pigment which collects in the 

 adventitious sheaths of the blood vessels and elsewhere is doubt- 

 less derived from the red corpuscles, which are colorless in these 

 cases. We are reminded of Miihlman's studies on the pigment- 

 ary metamorphosis of red corpuscles in the Arachnoid.^ The 

 yellow grains are found in the walls of the arachnoid vessels. 

 They are not soluble in chlorform but, unlike fat, partially dis- 

 solve in sulphuric and nitric acids. Tests with sulphide of 

 ammonia and potassium ferrocyanide demonstrate iron. The 

 author supposes that the pigment formation is due to a state of 

 irritation caused by pressure. They accumulate in the arachnoid 

 because there the texture is so slight as to submit them to pres- 

 sure. It might be supposed therefore, that the granules found 

 so generally in the clogged capillaries of paralysis are due to a 

 similar irritative cause. 



THE CORTEX. 



We may begin our examination by glancing at sections 

 from the tip of the temporal lobe (middle convolution). The 

 outer neuroglia layer differs little from that of the normal brain. 

 A careful study shows, however, numerous so-called spider cells 

 or scavengers, which here appear as multipolar bodies staining 

 faintly and lying closely involved in the mesh-work of the neu- 



^Zur Pigmentmetamorphose der rothen Blutkorperchcn. Beobachtungen von 

 dcr Arachnoides cerebralis. Virchow^s Arch. (12) VI, t. p. 160. 



