674 Proceedings of Royal Society of Edinburgh. [sess. 
counted subsequently from the moment of disappearance of the 
worm. 
Of these newts one was killed every half-hour for the first few 
hours, and subsequently at intervals of an hour. In this way, as 
far as was possible, every variant except time was eliminated, 
though not with complete success, for in a few cases it was after- 
wards found that some parasitic disease of the mucous membrane 
of the stomach was present, and those so affected were removed 
from the series. 
Method of Preparation . — At the prescribed time each newt was 
pithed, opened, its stomach, duodenum, and gullet removed with- 
out injury, and placed upon a piece of thin paper. The viscera 
were then opened by a longitudinal incision through their entire 
length; their contents, if any, removed, and the organs slightly 
spread out flat without stretching upon the paper, with the mucous 
surface uppermost. 
They were then immersed, paper and all, in Mann’s picro- 
corrosive fixing solution (modified formula, sp. gr. 1020), in which 
they remained till next day, when saturated corrosive sublimate 
(Heidenhain’s formula) was substituted for it. At the end of 
another twenty-four hours this was removed, and the tissue taken 
up the alcohol series into chloroform, and finally embedded in 
paraffin (58° C., Griibler). Longitudinal sections were then cut 
in series with the Cambridge rocking microtome set to four teeth, 
and fixed upon albuminised slides after spreading on warm water. 
To ensure equality in staining, and, therefore, comparability, one 
newt was used as a test object and all the slides stained up to it; 
the most efficient way of doing this is to place one section of the 
test newt upon each slide, and to see that in all cases that par- 
ticular section is stained to exactly the same tint. This test section 
may be placed at one end of the slide and subsequently wiped off 
before the other sections are finally covered. 
The sections were stained by immersion in various dyes, prefer- 
ence being given to Mann’s (16) methyl-blue eosine long method, 
and M. Heidenhain’s (7) iron alum, hsematoxylin, both long and 
subtractive methods. 
The photographs were all taken with a magnification of 600 
diameters. 
