Ba 
logical seminar of the Marine Biological Laboratory, Woods Holl, and 
before the Biological Club of the University of Princeton. 
I wish here to thank those who have helped me with this work. 
Members of the Marine Biological Laboratory and the U. S. Fish 
Commission at Woods Holl have rendered me invaluable assistance, 
and I would thank especially Prof. C. F. W. Mc Crure, Prof. Mac- 
LOSKIE and Prof. Lipsey of Princeton, Miss C. CLApp of Mt. Holyoke 
College, Mass., Dr. Epwarp GARDINER of Boston and Dr. OLIVER 
Strone of Columbia University, New York, for their kindness. 
Certain giant ganglion-cells have been found by neurologists in 
the dorsal wall of the spinal cord of several adult fishes. These cells 
may be situated on the edge of the gray matter of the dorsal horn 
or raised out of that and suspended by connective tissue in the dorsal 
part of the median fissure. They extend in these positions from just 
behind the union of the restiform bodies to a point caudad that varies 
in the different species. The function of these cells has been difier- 
ently interpreted in the different species, and the distribution of the 
neurites has also been reported to vary in nearly all of them. 
Such giant ganglion cells have been noted in the adult of Am- 
phioxus by many writers including STIEDA, ’73; VAN WIJHE, 793; 
Rnope, ’88; Rerzius, ’91; WıLLey, ’94; KOELLIKER, 793, etc., in 
Petromyzon and Myxine by REISSNER, ’60; FREUD, 77; AuHL- 
BORN ‚83, etc., in Lophius by Frirscn, ’86; in Orthagoriscus by 
HALLER, ’91; and Taciiant, ’94; in Tetrodon by HALLER, ’91, and 
others, in Trigla by Ussow, ’83, and others, and in Protopterus 
by BURCKHARDT, ’92. 
Again there are important papers on a larval or transient nervous 
apparatus in the embryos and young of many fishes. This apparatus 
consists of an aggregation of very large ganglion cells placed in the 
median dorsal wall of the embryonic or larval spinal cord. These cells 
are described as the first to assume ganglionic characters (BEARD, ’92; 
Ronon, ’85), to atrophy at an early stage of development (BEARD, 792, 
and others), and to possess neurites which probably pass out through 
the dorsal nerve roots or directly from the cells to the muscle-plates 
without entering fibre-tracts in the body of the cord; Brarp, ’96 
and ’92; Rowon, 85; HALLER, 95; KOELLIKER, "93; STUDNICKA, 795. 
The cells are usually placed in a double row in the dorsal fissure and 
this row extends from the medulla oblongata to points caudad which 
vary in the different species. 
These larval or transient cells have been described and studied in 
Salmo by Ronon, ’85; HALLER, 95; von Kuprrer, 93, etc., in Perca 
