46 Bulletin of Laboratories of Denison University. [Voi.xiii 



third order designed to distribute sensory excitations over a 

 large field of motor nuclei of the oblongata. Close to the raphe 

 in the median line is the fasciculus longitudinalis medialis, like- 

 wise composed largely of short paths and chiefly motor. Be- 

 tween this fasciculus and the substantia reticularis, there is ven- 

 trally the continuation of the ventral funicle of the spinal cord 

 and dorsally the lemniscus (funiculus lateralis, Fritsch; laterales 

 Langsbiindel, Stieda and Mayser). 



The lemniscus is very complex. It clearly is composed in 

 the main of crossed ascending fibers from the primary sensory 

 centers of the spinal cord and oblongata to the mid-brain. These 

 fibers correspond closely with the lemniscus lateralis or lateral 

 fillet of mammals. The lemniscus medialis, or direct pathway 

 to the cerebral cortex, as found in mammals, is of course not 

 present here and this whole ascending path I shall term simply 

 lemniscus. It probably receives fibers from the whole length 

 of the spinal cord with a large accession of similar fibers from 

 the funicular nuclei and enormous numbers of fibers from the 

 tuberculum acusticum. It receives no appreciable number of 

 fibers from the vagal lobes or other visceral sensory centers and 

 therefore may be considered a somatic sensory secondary tract. 

 It terminates in the mid-brain beneath the tectum in the pro- 

 tuberance into the optocoele which is so characteristic of the 

 teleosts and is termed the torus semicircularis (nucleus lateralis 

 mesencephali, Edinger). This body, in fact, seems to be 

 primarily the end-nucleus of this tract. Whether this bundle 

 also contains descending fibers I do not know, but am sure that 

 if present they are relatively few in teleosts. Such descending 

 fibers would of course have to be excluded from the designation 

 lemniscus.' 



Some of the smaller cyprinoids (e. g., Notropis) exhibit 

 but little enlargement of the vagal lobes. In the gold fish 

 (Carassius aiirat2(s^ the vagal lobe is greatly enlarged, but the 



' The reader will note that this tract is designated lemniscus on account of 

 its partial homology with the tract of that name in the mammals, and that it has 

 nothing to do with the so-called lemniscus of Mayser and others, or tractus tecto- 

 bulbaris et spinalis. 



