296 JOURNAL OF COMPARATIVE NEUROLOGY. 
1. No further mordanting. H. 12 hours. Osmic. Pal. Not 
good. 
(A) Pieces of cord mordanted eight days in copper bichromate. 
Sections made as in (a). 
1. No further mordanting. H.Osmic. Pal. Fair. 
2. Copper bichromate several hours (kept slightly warmed). 
H. 22 hours (first half hour in paraffine water-bath). 
Osmic: Pal. ‘Fine. 
3. Potassium bichromate-+ osmic several hours, etc., like 2. 
Not good, blurred and indistinct. 
{| (c) to (A) inclusive, taken from some incomplete notes made by 
my student, C. E. Doran]. 
(¢) Pieces of medulla and basal ganglia mordanted 7” fofo in 
copper bichromate 3% for seven or eight days. Sec- 
tions made as in (a). 
1. No further mordanting. N. h. 12 hours+Osmic. Pal. 
This invariably yielded fine results with a series extend- 
ing through the medulla and basal ganglia, practically as 
good as when remordanting in section was resorted to 
and without the added danger of brittleness. 
The following modification of the WeEIGERT method was 
devised by the writer in 1897 and has been found to be espec- 
ially adapted for his work upon the cranial nerves of Squalus 
acanthias. The head of an embryo at birth, cut longitudinally 
vertically in two pieces so as to just open one side of the cranial 
cavity, was hardened for about two weeks in iron alum 5% 
g vols. + formalin 1 vol. This fluid also decalcified. Although 
the material was somewhat brittle, a complete series of paraffine 
sections was successfully made. After fixing on the slide and 
successive removal of the paraffine and xylol, the slides were taken 
from the absolute alcohol and a thin solution of celloidin poured 
over them and off, thus covering the sections with a thin film 
of celloidin and absolutely preventing their removal from the 
slide during subsequent manipulations. This device, which had 
been used by the writer for some time previously to this, very 
much minimizes the danger of loss in staining serial paraffine 
sections. 
The sections were then stained, without further mordant- 
