is also lessened by leaving the dry peel on the specimen 
as long as possible—even two days is not too long. The 
shrinkage of a peel 50 millimeters long is approximately 
2 millimeters if drying has taken less than 12 hours. The 
other difficulty has been indicated before, that is the de- 
velopment of air-bubbles. This is chiefly overcome by 
mixing a slow-drying solution with Parlodion, such as 
that recommended, and by thoroughly drying the speci- 
men before applying the nitrocellulose solution. It is 
sometimes helpful to moisten the surface with butyl] ace- 
tate. Collodion and similar substances invariably develop 
many small bubbles, because of their rapid drying nature. 
In addition to these purely paleobotanical uses of the 
peel technique, there are many interesting applications 
in other fields of work. We have tried similar methods 
on recent and fossil animals with calcareous parts and on 
anthropological material such as carbonized grains and 
sun-dried bricks. Some petrographic observations can be 
readily made with the peel technique. 
To my wife, Helen Hilsman Darrah, I wish to extend 
thanks and to acknowledge her part in the development 
of various phases of this nitrocellulose peel technique. 
[ 83 | 
