JOKES’ METHOD OF PRESERVING TISSUES 87 
THE APPLICATION OF JOKES’ METHOD OF PRESERV- 
ING TISSUES IN THEIR NATURAL COLOURS TO 
NATURAL HISTORY SPECIMENS 
By Dr. P. H. Ross and Mr. A. Blaney Percival 
Jores’ method of preserving tissues in their natural colours 
consists in placing the specimen in the following fixing solution : 
Sodium chloride 
Magnesium sulphate 
Sodium sulphate 
Distilled water 
Formalin 
1*0 
2*0 
2-0 
100-0 
*5 to 10 parts 
In this solution the specimens are left for a time, depending 
on their size, the larger the specimen the longer being the 
time. In this solution the colour gradually becomes grayish, 
but on transferring the specimen to methylated spirit for 
from one to six hours the original colour returns, and the 
specimens are then put into a mixture of equal parts of glycerin 
and water, in which they are preserved. At no time during 
the course of the preparation are the specimens washed in 
water. Plenty of the fixing solution should be used. 
Some seven or eight years ago it occurred to one of us 
(P. H. R.) to try whether the ordinary methods of preserving 
pathological specimens in their natural colours could not be 
applied to natural history specimens. A large brilliantly 
coloured praying mantis was prepared according to the method 
of Jores (‘ Centralblatt f. path. Anat.’ Bd. VII. 1896, S. 184), 
and sent to the British Museum. Judging by the description 
of the colours on arrival at the British Museum, the method 
was entirely successful, so far as concerned the preservation 
of the colour. 
Objections are raised against the use of formalin for natural 
history specimens, on the grounds (1) that the specimens 
become too stiff for examination ; (2) that though the colour 
may be retained, the markings are lost ; (8) that the specimens 
finally perish in formalin. 
