62 NERVE COMPONENTS OF BONY FISHES. 



rend dieses intracervicalen Verlaufs sendet genanntes 

 Biindel vereinzelte Collateralen aus, die sich nach innen 

 zu in einen kleinen, ungenau begrenzten, sehr dicht an 

 der hinteren Commisur gelegenen Herd grauer Substanz 

 verzweigen." 



A comparison of this description and the accompanying 

 figures with the relations in the fishes which I have exam- 

 ined (including Mugil, Haploidonotus and Fundulus) 

 very strongly suggests that the commissura infima Halleri 

 contains the homologue of the commissure of Cajal's 

 Commissiire?ikern. I am inclined to accept this homology, 

 recognizing, however, that the commissura infima con- 

 tains other fibres than those pertaining to the fasciculus 

 communis. Whether the cells found in this region in 

 fishes are homologous with the cells of the commissural 

 nucleus of the mouse, I would not venture to guess. 



Mayser ('8i, p. 296) recognized the intimate relation of 

 the commissura infima in the cyprinoids with the lobus 

 vagi and the vagus nerve. The caudal portion of the 

 commissure he inclines to regard as in part a decussation 

 of the spinal V tract and in part a commissure of the dor- 

 sal cornua of the spinal cord. This I can confirm; i. e., 

 I find medullated fibres entering the commissure from the 

 cephalic portion of the nucleus funiculi. They are proba- 

 bly secondary fibres. Niedzvietzky ('97, p. 542) has more 

 recently described in the rabbit a commissure containing 

 medullated fibres between the lower or caudal ends of the 

 two fasciculi solitarii. A similar condition has been 

 previously noted by Koch ('92) in the bird. 



The homologies proposed in the preceding section may 

 be summarized as follows: 



(i). The fasciculus communis and its related struc- 

 tures (including the lobus vagi and the chief vagus roots) 



