14 
laboratory. A little fine hardwood sawdust mixed with the borax econo- 
mizes borax, keeps it from becoming lumpy, and aids in drying the skin by 
absorbing dampness and the small residue of grease that is apt to remain 
on the skin. The borax and sawdust mixture is effective without the 
naphthaline. Too much reliance should not be placed on the naphthaline, 
because although it is a fairly effective deterrent to most pests when 
used in quantity, the small amount in a preserved skin will soon evaporate 
and the skins need to be kept permanently in an insect-proof case. 
Napthaline is the main constituent of the ordinary moth-ball, which may 
be used in cases of specimens when naphthaline flakes are not available, 
but the flakes are cheaper and being much more volatile are generally 
more effective. 
Common salt is useful for temporary preservation, is obtainable any- 
where, and is the best medium for preserving the fresh hides and scalps of 
large mammals. Salt may be used for preserving any kind of skin, and 
the finer the grain the better. Table salt is best for small animals, and 
ordinary barrel salt will do for large specimens. It should be applied 
plentifully and as soon as possible after skinning. A 2- or 3-pound con- 
tainer of one of the brands of table salt that will not become lumpy will 
preserve a considerable number of small specimens and may be poured out 
of a funnel without waste. Major Allan Brooks (in letter, 1935) advises 
that borax should never be used on mammal skins as it turns the fur red. 
He states that kangaroo rats ( Dipodomys ) from Death Valley, California, 
are a red race, but Mr. A. J. Van Rossem had shown him the year before 
that the same reddish type can be produced by using borax in the make-up 
of the skins of other races of the same genus. The writer was informed 
in 1937 that collectors for the Royal Ontario Museum of Zoology, Toronto, 
were using borax only on bird skins. Downing (1945) sums up experiments 
in the same institution relaxing and re-making skins of both mammals and 
birds that had been preserved with arsenic, arsenic-and-alum, alum, borax, 
and salt. His conclusion is that skins of many species of mammals, particu- 
larly the Sciuridae (squirrels) and other species with reddish or brown 
hair that have been relaxed and remade suffered changes in colour that 
renders them almost useless for taxonomic studies where colour is an 
essential character. Similar changes in colour were found to occur in 
plumages of remade specimens of several birds in different groups with 
reddish or brown colours. He states that the extent of the change in colour 
appears to depend on the length of time the hair is in a moist condition, 
and that it may be possible by rapidly relaxing, washing, and drying to 
avoid producing any colour change. This problem requires further investi- 
gation. In the meantime any specimen that is relaxed and made over or 
washed in the process of preparation should bear this information on the 
label. 
An experiment checked by the writer on skin of red squirrel, freshly 
killed, and split down the back, one-half immersed in pure “soft” lake 
water all night, and dried, showed no perceptible difference in comparison 
with the half of the skin that was not wetted. It may be that borax or 
soap in water relaxing a skin, may remove some of the natural oil from the 
surface of the hair and make it more subject to change of colour in pigment 
cells. Chlorinated tap water may also have some effect in changing the 
colour. 
