XXviii JOL'RNAL OF CoMPAKATI\K NeUROLOGV. 



when mature, the corresponding nidiili are found to be degenerated. In 

 this wav Gudden has identified the niduli of the nerves of the eye- 

 muscles, Ganser discovered a degeneration of retinal elements after 

 section of the optic tracts, Monakow demonstrated degeneration of the 

 cortical pyramidal cells after section of the pyramidal fasciculi, and 

 Mendel corrected Meynert's account of the acoustic. 



The experiments described in the present paper were all by the 

 second method, and related to the ninth, tenth and twelfth nerves. The 

 section of one of the roots of the latter in the young causes entire 

 loss of the nidulus, though without aftecting the small-celled hypo- 

 glossus nidulus of Roller, and proves that there are no crossed fibres. 



There is no connection with the olives, and the various parts of the 

 true nidulus (Stilling's nidulus) are not connected with each other or 

 the opposite side. 



The author denies (somewhat inconsequently, we think) any con- 

 nection with the nidulus of the lateral fasciculus, nidulus of the vagus, 

 or dorsal longitudinal fasciculus. 



Extreme diflicultv attends experimentation upon the ninth and tenth 

 and it is usually impossible to avoid injury to the eleventh. Mayser, 

 however, succeeded in extirpating the ninth and tenth, and our author 

 figures and describes the sections of one of these brains. 

 ' The definite results are the following: 



1. The sensory fibres of the lateral mixed system (IX-XI) spring 

 from the fascicularis solitaris or respiratory bundle and end between the 

 cells of the surrounding gelatinosa. 



2. The motor fibres of the vagus and glosso-pharyngeal spring from 

 the nidulus cephalad and dorsad of the hypoglossus nidulus. 



3. There is no decussation in either case. 



The Development of the Spinal Ganglia in Man. 



Lenh6ssek(i) has availed himself of the section of a human embryo 

 2.5 mm. long and possessing twenty myomeres to discuss anew the 

 origin of the spinal ganglia. The results may be thus summarized. At 

 an early period the material of the future ganglia separates in the form 

 of an unsegmented band on either side of the medullary plate. It is 

 distinguished by its spherical cells — ganglioblasts. The closing of the 

 plate to form a tube brings the two bands toward each other, and results 

 in a temporary union. Soon, however, a rapid proliferation of the cells 

 results in a return to their lateral position and an indication of segmen- 

 tation. The method described is similar, except in unimportant details, 

 with that described in other groups by His and Beard. The author, 

 however, believes that the medullary nerve plate includes the germs of 

 the sympathetic system, as well as of the central and peripheral. 



I Lenhossek, M. v., " Die Entwickeluiig der Ganglienanlagen bei tlcni menscliliclicn 

 Embryo," Archiv f. Anat. und Phys., 1891, I. 



