CHANGES IN THE NISSL’S SUBSTANCE OF THE GANGLION 
AND THE BIPOLAR CELLS OF THE RETINA OF THE 
BRANDT CORMORANT RHALACROCORAX PENICILLA- 
TUS DURING PROLONGED NORMAL STIMULATION. 
BY G 
A. J. CARLSON. 
From the Hopkins’ Seaside Laboratory and the Physiological 
Laboratory of Leland Stanford, Jr., University. 
WitH 1 CoLORED PLATE. 
Beginning with the work of Hodge numerous researches have been 
made on the histological and micro-chemical changes in ganglion cells 
in different states of physiological activity. Both the changes observed 
as well as their interpretation are in many respects at variance, which 
may, in part, be due to the different methods employed, but probably 
also to the fact that the states of rest, activity and fatigue of the cell 
as typified by change in structure and chemical reaction are probably 
separated by imperceptible gradations only. As electrical stimuli were 
in many cases resorted to bring about the conditions of activity and 
fatigue of the cells. Nissl* in 1896 pointed out the invalidity of, 
without further proof, identifying the changes observed in the cells on 
such treatment as identical with the changes that may accompany nor- 
mal physiological functioning. The vertebrate retina seems to offer 
the best field where conditions of rest, activity and fatigue may without 
much difficulty be induced by variations in the normal physiological 
stimulus. The first investigator to study the finer structural differences 
in the cells of the stimulated or fatigued and of the resting retina was 
Mann (1894).° He did not confine his observations to the retina, but 
1This work was begun in the fall of 1900 at the suggestion of Prof. F. M. McFar- 
land. It was intended to extend the observations to the retinae of reptiles and 
fishes, but as other work has intervened the note is recorded in its present form. 
“For a recent résumé of the literature the reader is referred to an article by Van 
Durme: Etude des differents états fonctionnels de la cellule nerveuse corticale. Le 
Wevraxe, II, 1901, pp. 125-142. 
3Nissl: Die Beziehungen der Nervenzellsubstanzen zu den thatigen, rnhenden and 
ermiideten Zellzustinden. Neurologisches Centralblatt, 1896, 8. 59. 
Mann: Histological changes induced in sympathetic, motor, and sensory nerve 
cells by functional activity. Journal of Anatomy and Physiology, 1895, p. 100. 
