Johnston, TJ?c Radix Mcsejicephahca Trigetnini. 597 



directed downward and grows more slender. As the fibers approach 

 the motor nucleus thej give off branching collaterals which form a 

 rich plexus in this nucleus. Most of the fibers give from two to four 

 collaterals to the motor nucleus, some divide into two nearly equal 

 branches, one of which enters the motor nucleus, the other going on 

 with the motor root. !N"one of the collaterals go beyond the motor 

 nucleus, and none turn toward the raphe to form a motor decussation. 

 "I^ach unserem Dafiirhalten ist diese interessante Anordnung der 

 motorischen Collateralen fast einzig in ihrer Art ; in den Wurzeln des 

 Facialis, des Hypoglossus und des Oculomotorius sahen wir sie nie- 

 mals und bei den vorderen Wurzeln der Medulla spinalis ist sie sehr 

 selten" (p. 16). 



Wallenberg (1904) describes descending degeneration (Marchi 

 method) of the mesencephalic root in the pigeon and the duck after 

 lesion in the tectum mesencephali. He states that the bundle sends 

 a few isolated fibers into the median nucleus of the cerebellum and that 

 while the most of them go out of the brain with the motor root of the 

 trigeminus, some fibers go on caudal to the level of the "Cochlearis- 

 Eckkernes," where they end in the formatio reticularis near the motor 

 cells. He mentions that Probst has seen similar fibers to the formatio 

 reticularis caudal, to the trigeminus in mammals. It should be 

 noticed that the author states (1. c, p. 526-7), "war es mir bei 5 

 Tauben und 2 Enten durch Anatzung resp. Anstich lateraler Telle 

 der Rinde des Lobus opticus bis an das Wandungsgrau des Seiten- 

 ventrikels moglich, Easern der cerebralen Quintuswurzel an ihrer 

 Ursprungsstelle zu zerstoren und sie als dicke schwarze Biindel bis 

 zum Austritt aus der Briicke und in den Bulbus hinein zu verfolgen." 

 From this it appears that the exit of these fibers with the motor root 

 of the trigeminus was not shown by the Marchi degeneration method, 

 but rests on other methods. 



Just as this paper is being put in final shape for the printer I have 

 received through the kindness of the author a paper by Telle (1909) 

 in which he figures the cells of origin of the mesencephalic root in 

 teleosts (Salmo trutta). The figure agrees with my findings in 

 Acipenser and young teleosts and Amia. The author makes no 

 reference to Van Gehuchten's paper and his observations are evidently 

 an independent confirmation of Van Gehuchten's results. 



