THE BRAIN 179 



examined microscopically, and no lesions of any sort were 

 found. Ceelen, however, reports the finding of typical typhus 

 " nodules" in the choroid plexus. 



The histology of these proliferative lesions has received 

 much study by Ceelen (1919), Nicol (1919), and Spielmeyer 

 (1919). All are agreed that the lesion is primarily a reaction 

 on the part of the neuroglia. Both Ceelen and Nicol concluded 

 that the proliferative lesions take origin in lesions, or at the 

 site of lesions, in capillaries and pre-capillaries, a conclusion 

 which we unreservedly corroborate. Spielmeyer believes that 

 the lesions arise independently of processes localized in blood 

 vessels. He describes four types of lesions all proliferative in 

 character. The common or typical lesion he calls the compact 

 lesion. This type is the small tubercle-like lesion, which usually 

 extends through seven to eight 15-micron sections in series. 

 They measure 0.1 to 1.5 microns in diameter, though much 

 smaller ones are found. His rosette forms are small lesions 

 extending through two or three sections only and are formed 

 by rod-shaped and sausage-shaped neuroglia cells distributed 

 radially about capillaries. This type of lesion is most common 

 in the superficial layers of the cerebral and cerebellar cortex. 



A lesion practically limited to the molecular layer of the 

 cerebellum, though occurring in the superficial layer of the 

 cerebral cortex, is described by Spielmeyer as "strauchartiges" 

 or a "Gliastrauchwerk" (bush-like or glia bush work). This 

 lesion consists of a diffuse neuroglia increase in small areas, 

 about 0.1 mm. in diameter, and was found in distinctive form 

 in but one case, though present to some degree in four other 

 cases in his series of thirteen brains. His fourth type of lesion 

 is that called "Gliastern" (glia star) and consists of a single 

 or double layer of glia cells surrounding a pre-capillary. The 

 cells may be radially arranged and thus the lesion may resem- 

 ble a small rosette lesion. The glia stars are small, extend 

 through one or two 15-micron sections and are commonest in 

 the pons and spinal cord. The glia stars and the glia bush work 

 (Gliastrauchwerk) lesions are not restricted to typhus, but are 

 found also in typhoid fever. 



