must be diseased to produce sufficient resin for amber ac- 
cumulations. Furthermore, present-day ecological studies 
need to be made on the types of material that become in- 
corporated in resin, as well as on the conditions under 
which the resin is preserved. 
SUMMARY AND CONCLUSIONS 
Despite man’s interest in amber from earliest times, 
relatively little is known about the plant sources of the 
resins and types of forests in which the trees lived. Evi- 
dence for the kinds of trees producing the resin may be 
derived from four sources: 1) chemical character of the 
amber; 2) inclusions in the amber; 8) fossils from the 
amber-bearing beds; 4) habitats and general nature of 
resin production from possible modern equivalents. Evi- 
dence for composition of the forest may be obtained from 
both the inclusions and the fossils in the amber-bearing 
beds, if these beds have not been secondarily deposited, 
and from the habitats and general associates of the possi- 
ble modern equivalents. Because amber is considered a 
gem, the mineralogist has been largely responsible for its 
routine chemical and physical characterization, resulting 
in data which are usually not useful in determining plant 
source. Only recently has the desirability of including 
plant source as an important criterion in a mineralogical 
classification system been expressed. 
Ambers have been reported from Cretaceous to Pleis- 
tocene deposits throughout the world. In most cases, 
however, the geological age is not well documented, and 
discussion of plant source is avoided. The primary inter- 
est, other than mineralogical description, has been dis- 
cussion of insect inclusions. With the possible exception 
of the Baltic amber,synthesis of data pertinent to answer- 
ing the botanical questions has not been attempted. 
The Baltic deposits are the most extensive known and 
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