88 JOKES’ METHOD OF PRESERVING TISSUES 
This may be true for specimens that are kept altogether 
in formalin, but does not appear to apply to specimens pre- 
served by Jores’ method. Some months ago specimens of 
Tilayia mozanibica, brought by Mr. Graham from Lake Magadi, 
were preserved, some by this method and some in alcohol. 
At the present time the Jores’ specimens are as fresh as when 
received, their markings and colour being as clear as ever, 
while the alcohol specimens have lost all their freshness and 
most of their colour. 
More recently one of us (A. B. P.) collected a large number 
of specimens from the Northern Uaso Nyiro and district, some 
in alcohol, some in a mixture of salt solution and 5% formalin, 
the proper mixture of salts not being obtainable at the time. 
In these solutions the specimens remained for up to four 
months, and, on return to Nairobi, the formalin specimens 
were put through the spirit into glycerin and water (equal 
parts). All specimens appear as fresh as when caught, and 
such specimens, as fish, are no stiffer than when landed. The 
spirit specimens, on the other hand, have most obviously 
deteriorated in colour, even in these few months. 
The final value of the method can only be told when suffi- 
cient time has elapsed for us to see the degree of permanence 
of the colour, but the marked superiority of the formalin over 
the spirit specimens after a few months is most marked, and 
the convenience of the Jores’ method can only he appreciated 
by one who has tried carrying round quantities of spirit in a hot 
country, where transport is a constant difficulty and every 
pound has to be considered. The salts can be carried dry, 
the formalin in its usual form as 40% formaldehyde. Distilled 
water does not appear to be essential since the last specimens 
collected do not appear to have suffered from the salts and 
formalin having been mixed with whatever happened to be the 
drinking water of the place where the specimens were collected. 
Naturalists, who intend making collections of fish, are 
strongly recommended to give this method of preservation a 
trial, as the results are most satisfactory. 
