percent hematoxylin solution to help bring out 
the identification features of plant fragments 
in microtine stomach contents. 
Reference photomicrographs of plant tissues 
will help greatly in the identifications. Black 
and white photomicrographs are used, mainly 
because of cost and use in publications. Color 
transparencies are good for teaching aids and 
for illustrating work in slide talks. 
Stomach contents or fecal materials can be 
examined dry or wet. The method used depends 
on the way the material has been stored and on 
individual preference. I prefer them fresh and 
wet. If the contents are fresh or have been 
frozen, they are first washed in water to rinse 
off digestive juices. If formalin has been used, 
the contents should be rinsed in running water. 
Fresh materials do not break into small frag- 
ments as they often do when dried. 
Identification 
Identification of food items is difficult and 
critically important. Experience and judgment 
are significant assets in identification. Many 
times, especially with large animals, a good 
sample of leaves, twigs, stems, or seeds can be 
selected; the sample should be easily identified 
and should help in the identification of the 
smaller fragments. The classifications should 
be as specific as possible. However, broad clas- 
sifications are important. In many studies, the 
material listed as unknown could at least be 
classified as plant, animal, or soil. When work- 
ing with herbivores, for example, classification 
into broad groups, such as grasses, forbs, or 
shrubs, is often possible, and such information 
is important. 
In food-habits studies of grasshoppers, ro- 
dents, rabbits, sheep and cattle, the microtech- 
nique and histology methods have been used. 
These methods have been particularly useful 
when working with small animals and rumi- 
nents that grind their food into small frag- 
ments. The first step is to study reference ma- 
terial to become familiar with known plant 
histology. Time thus spent will not be wasted. 
A key based on distinctive differences in sto- 
mata, hairs, cell configuration, size, and other 
morphological characteristics can be made to 
help in identification. 
A procedure of analysis cannot be standard- 
ized for all species of herbivores. These species 
are many sizes and eat and chew their food in 
many ways. For elephants, the food material 
may be separated with a fork; for seed-eating 
birds, the seeds can be separated by screens or 
by hand picking; for small mice, separation of 
plant fragments may not be practical. To sat- 
isfy all conditions, the procedures have to be 
modified and restricted. 
The amount of time required to train an in- 
dividual to do examinations depends on the 
methods being used, the animal being studied, 
and the experience and interest of the person. 
Material collected from the fistula of a cow is 
much easier to work with and identify than 
plant fragments from a pocket gopher stom- 
ach: 
Galt et al. (1966) reported that it took 24 
hours to take 1,600 points and 6 hours to take 
400 points by the microscopic-point method de- 
scribed by Heady and Torell (1959). These 
identifications undoubtedly were made by an 
experienced worker. Students examining 
pocket gopher stomachs and Wiley-milled ma- 
terial from rabbit stomachs and cattle fistula 
have commented that it takes about 2 months 
of intensive study of reference material before 
moderate progress is made in identifying plant 
fragments. The speed and efficiency improve 
with experience. It is advantageous for the 
person doing the examinations to participate in 
the collections. 
The reference collection should be consulted 
frequently. There are no good illustrated refer- 
ence publications for plant fragments. Herbar- 
ium specimens collected from study areas are 
the most useful and provide more accurate 
identification. An important aid in the iden- 
tification of seeds is the Seed Identification 
Manual (Martin and Barkley 1961). A collec- 
tion of known seeds is better. 
The first few stomach contents in any study 
will be the most difficult to identify. Do not 
spend a lot of time trying to identify puzzling 
fragments. Often, after the larger or more 
characteristic items are identified, close exami- 
nation shows that the finely divided materials 
are parts of the larger, already identified food 
items. 
The extent of segregation of food items var- 
ies with the investigator, objectives, and the 
method of analysis being used. For purposes of 
this discussion, the methods will be considered 
on the basis of the magnification used to iden- 
tify food materials. 
No Magnification or Very Low Power 
Naturally, this method has limitations. For 
example, small rodents that grind their food 
into very fine fragments cannot be studied by 
this method. Food habits of large herbivores 
and birds are very often examined without the 
aid of high magnification. 
Various methods have been used to segregate 
materials from large herbivore stomachs. It 
has always been questionable what should be 
done with the unidentified mass of finer items. 
Some workers separate the coarse items by use 
of one-eighth inch mesh sieves, and do not use 
the fine materials in their analvsis (Dirschl 
1963; Cole 1956; and Cole and Wilkins 1958). 
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