416 TRANSACTIONS OF THE CANADIAN INSTITUTE. [VoL VI. 
pigment in their body. The pigment has been found to be especially 
common in man and monkeys. (Warrington).“*" The pigment present 
in the cells of a thoracic sympathetic ganglion of an ox, after it had 
been hardened in alcohol, gave the following reactions. It was still 
present after a one per cent. solution of potash had acted on loose 
sections for three days at room-temperature. It was not removed from 
the free sections by the action for a week of one per cent. hydrochloric 
acid solution, nor did it give, after the use of acid alcohol, any reaction 
for iron, which confirms what Warrington found for the pigment present 
in the nerve cells of man. It did, however, give a positive reaction for 
phosphorus, using Macallum’s test. ~ 
Before leaving this section I would like to discuss the structure of the 
nucleolus. There is always one, and there may be several, nucleoli 
present in the nucleus of the nerve cells of mammals and in most other 
classes of animals; but there is rarely a nucleolus in the nerve cells of 
the Urodela and if present it cannot be distinguished with certainty 
from the remainder of the nuclear chromatin. 
The nucleolus is considered by most observers to consist of a single 
substance which may be vacuolated. Several observers, however, have 
described the nucleolus as consisting of fine grains embedded in a ground 
mass. This view is supported by v. Lenhossek,* Held,” Ruzicka,“ 
Obersteiner,” but more particularly by Timofeew* who says the 
nucleolus consists of basophile grains embedded in an oxyphile ground 
substance. 
The nucleolus consists of two substances, but the relation of these two 
is different from that usually described. I find the nucleolus is a vesicle 
with an oxy-centre and a basophile covering.” This relation is often seen 
in sections stained with eosin and toluidin blue, or in material fixed in 
Flemming’s fluid and stained with his orange method. A somewhat 
similar structure has lately been described by Heimann*, who noticed 
the periphery of the nucleolus had a great affinity for stains. 
This structure is best seen in the nerve cells of rodents but occurs in 
41 Warrington, W. B. ‘‘On the Structural Alterations observed in Nerve Cells,” Journal of Physiology, 
XXIII, 1898. 
42. v. Lenhossek, |. c. 
43. Held, Archiv f. Anat. u. Physiol., p. 207, 1897. 
44. Ruzicka, Zeit. t. Wiss. Mikroskopie, p. 452, 1897. 
45. Obersteiner, Zeit. f. Wiss. Mikroskopie, p. 60, 1808. 
46. Timofeew, l.c. 
47 Mackenzie also observed this relation in the nucleolus. Oral Communication, British Association, 
Toronto Meeting, 1897. 
48 Heimann, |. c. 
; 
