1038 



corresponds to our exj^eiieiice that this tract cannot he traced in 

 AVeigert-preparatioiis. 



In most Teleosts this tract is \er\- considerably developed and 

 Hekrick has described it tliere in a masterly way under the name 

 of ascending secondary gustatory tract. 



It is this tract which has the gi-eatest M influence on the ventral 

 shifting and perhaps on the frontal isolation of the Vll nucleus in 

 Teleosts. It can even be demonstrated that the ventral migration of 

 that nuclens (as well as of the V nucleus) is more conspicuous and 

 more complete in those Teleosts, where this gustatory tract is more 

 developed. 



On account of this fact it is not astonishing that in animals where 

 the ascendim/ gustatory system is only relatively poorly developed 

 a ventro-frontal migration of the VII nucleus has not yet occurred. 

 It seems probable to me that in Ganoids as in Selachii the secon- 

 dary neurones of the sensory VII-IX — X nuclei are partly short 

 intej-calating neni'ones, while the longer secondary neurones of the 

 viscerosensory nucleus may ha\e chiefly a descending character. 



It seems useful to me to give here also the topographic reconstruc- 

 tion of a young specimen of Lepidosteus osseus which the Institute 

 received from Mr. Edw. Phelps Allis in Menton. 



I had at my disposition two specimens, of 5 and 10 cm. The 

 specimen of 5 cm. being better preserved, I shall only give the recon- 

 struction of this. I may add, however, that the 10 cm. specimen 

 did not differ in any principal point from this, so that I got the 

 conviction that the definite arrangemeiu of the motor nuclei is already 

 present in the 5 c n\. specimen as far as concerns its jtrincipal features. 



Also in Lepidosteus the oculomotor nucleus extends a considerable 

 distance in front of the level of its root. The cells lie on the 

 dorso-lateral border of the fasciculus longitudinalis, very near the 

 ventricle. There is a difference in so far that the slight indication 

 of a ventro-medial nuclens present in the fullgrown Amia and Aci- 

 penser fails in this young Lepidosteus. Perhaps this diflerence is due 

 to the young stage of development. 



As in the other ganoids there is a considerable gap between the 

 III and IV nucleus, although the tractus cerebello-mesencefalicus 

 dorsalis does not run between it. ') The trochlear root lies again a 

 good deal behind its nucleus. 



1) Not the only influence though. Some other tiacts (e. g. an ascending sensory 

 tract from the cervical region) may also run near the descending V. 



'-) Since there is no real valvula cerebelli in Lepidosteus this tract, it present, 

 takes a more caudal couise. 



