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commissure of ganoids and teleosts, and it is clear that there has 

 been a fohling down and hypertrophy of the velum to form the valvula. 

 This is supported by the mode of development of the valvula in teleosts. 

 At the same time the tract from the inferior lobe entered the same 

 region. The relative influence of this and the visceral tract from the 

 medulla oblongata in producing the growth of the valvula, is not clear. 

 It seems probable is that here in the cerebellum tracts from centers 

 with visceral functions do not enter the same center with tracts having 

 somatic functions. The valvula is a part of the visceral division of 

 the brain, the remainder of the cerebellum belongs to the somatic 

 division. What connections may exist between the two portions of 

 the cerebellum remain to be worked out. It is an interesting question 

 whether the valvula has not been formed by a shifting mesially of 

 elements from the secondary visceral nucleus along the commissure. 

 In Acipenser some cells of the nucleus send dendrites in the commis- 

 sure half way across the valvula. Such an origin for the valvula might 

 be expected if it is compared with the nucleus commissuralis of Cajal, 

 which is found at the caudal boundary of the fourth ventricle in all 

 vertebrates. This nucleus is developed in the median dorsal region 

 in connection with the visceral sensory columns and is traversed by a 

 commissure of fibers from those columns in the medulla oblongata. 

 It is probable that both the nucleus of Cajal and the valvula have 

 been formed by upgrowths of the visceral sensory column along the 

 commissures. In essentially the same manner it is believed that the 

 somatic portion of the cerebellum has been formed from the acusticum. 

 Putting aside details, the main fact is clear, the valvula exists in those 

 forms in which the gustatory organs are highly developed and Herhick 

 was right in his surmise that it was called forth in response to gusta- 

 tory impulses. The tract from the inferior lobes probably brings ol- 

 factory impulses also. A relation of any part of this apparatus to 

 the optic tract, which Edinger suggests, .is very improbable. 



A brief comment is necessary upon Edinger's account of the re- 

 lation of the cerebellum to the sensory cranial nerves. Several authors 

 besides those cited by Edinger had described the entrance of direct 

 sensory root fibers into the cerebellum. Trigeminus fibers going to 

 the cerebellum in amphibia had been described by Wlassak and 

 Gaupp; acusticus fibers by Koeppen, Osborn and Gaupp. Gorono- 

 wiTSCH had described the direct cerebellar fibers of the trigeminus in 

 Acipenser and Lota. The writer described in detail in 1898 the re- 

 lations of the trigeminus, acusticus and lateral line roots to the cere- 

 bellum and showed that the cerebellum is an enlarged continuation of 



