Dahlgren, Giant Ganglion Cell Apparatus. 179 



LopJiins was then examined and the missing caudal fiber was 

 immediately discovered. This fish, PtcivpJiryne Jiistno possesses 

 only 24 giant cells which is the smallest number yet found in 

 an adult teleost fish. These cells are very large and closely re- 

 semble those of Lophius in every particular. Having demon- 

 strated this bifurcation of the giant cell neurite in these two 

 forms, it is probable that the same will be found to hold true 

 for the other fishes possessing this apparatus. 



The number of species in which the giant cell apparatus 

 appears, has been found to be far greater than supposed. A 

 vast number of teleost fishes possess it and the writer does not 

 hesitate to estimate that this number is over one half of the 

 living species. It is found less frequently in the lower orders, 

 the Nematognathi, for instance, not showing one instance as yet 

 in which it has been found; while the Pediculati and Hetero- 

 soMATA fail to yield one species which does not possess it in a 

 highly differentiated and developed form. Where found in a 

 more primitive form it is characterized by the large number, 

 small size, and simple structure of its ganglion cells, while in 

 the specialized forms the ganglion cells are fewer and of mon- 

 strous proportions and uncouth structure. 



Its relation to the "Transient Ganglion Cells" or "Trans- 

 ient Nerve Apparatus," described in Sahno, Raja, etc. by Ro- 

 hon, Beard, Van Gehuchten and others, is clearly, in the 

 writer's mind, one of identity ; the giant cell apparatus being 

 composed of some or all of the transient cells which have re- 

 mained. 



Van Gehuchten's discovery of the bifurcation of the neu- 

 rite of the transient ganglion cells of Sahno must therefore be 

 considered the first exposition of this fact for the giant cell ap- 

 paratus as well. 



Many embryonic fishes have been found to possess the 

 transient apparatus and the writer doubts if any form of teleost 

 is without it. Work will be continued on Psaidoplcuroncctes 

 Am. and other forms. 



