24 ARISAEMA TRIPHYLLUM 
DEVELOPMENT AND LIFE OF THE CORM 
In a brief paper before the regular winter meeting of the 
Indiana Academy of Science in 1912 (19) the writer suggested that 
the life of the corms of A. triphyllum was fairly definitely fixed, 
no part of the corm probably being more than four years old. 
Wider observations of mature corms along with a study of the 
development of corms in seedlings makes it possible to add materi- 
ally to the report cited. 
MacDougal (17) and Rennert (22) have given quite full accounts 
of the germination of seeds of A. triphyllum and A. Dracontium and 
the development of the seedlings. The author has verified the find- 
ings set forth in the 
two papers mentioned, with some minor 
exceptions to be noted below. The findings of MacDougal and 
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. 28. The phello- 
derm layer forming beneath 
the epidermis, E, of a first 
year corm. X 60. 
Fic. 28a. An old layer 
of phelloderm, P’, and a 
new layer, P”, forming 
within and cutting off the 
exhausted starch cells, S. 
R, a raphide cell. X 60 
Rennert for A. triphyllum may be briefly 
summarized as follows: In the presence 
of moisture and suitable temperature the 
seeds swell, and the outer rows of testa 
cells are dissolved. The starchy endo- 
sperm, protected from external agents by 
the tannin impregnated cellulose layer of 
the testa, is dissolved by diastase formed 
by the epithelium of the imbedded em- 
bryo. Within the embryo the cotyledon 
elongates by a lengthening of its cells and 
pushes the hypocotyl and plumule bud 
from the seed. By a curvature of the 
cotyledon just outside the seed its point is 
directed downward. The hypocotyl en- 
larges as a result of the increase in size and 
number of its cells. By active division of 
the procambium cells both in their longi- 
tudinal and transverse diameters much new 
tissue is rapidly formed. The fibro-vas- 
cular system, raphide cells and storage cells 
are soon differentiated, while a layer of periderm (TEXT Fic. 28) 
consisting of five or six layers of empty flattened cells arises on 
the outside of the enlarged portion and finally separates the newly 
formed corm from the cotyledon. 
While these changes have been 
