THE ORIGIN OF THE CHLOROPLASTS IN THE COTY- 
LEDONS OF HELIANTHUS ANNUUS 
EDWIN C. MILLER 
(WITH PLATE XXI) 
There are two prevalent opinions in regard to the origin of 
chloroplasts in seedlings. One group of investigators holds the 
view that the chloroplasts originate directly from the cytoplasm 
of the cell. According to them, the mature seed from which the 
seedling originates contains no chloroplasts. They hold that if 
any chloroplasts are present in the young embryo, they lose their 
color and disintegrate at the ripening of the seed, and that at 
germination the protoplasm in the cells of the cotyledons gives 
rise to new chloroplasts which function during the period of activity 
of these organs. The other group of investigators maintains that 
the protoplasm of the cell never gives rise to chloroplasts, but that 
the fertilized egg contains chromatophores which have been 
derived directly from the parent plant. During the development 
of the egg into the embryo these chromatophores multiply, and 
in this manner provide every cell of the embryo with chroma- 
tophores. In many seeds before maturity the chromatophores 
have become differentiated into chloroplasts, which are plainly 
visible. During the ripening of these seeds their chloroplasts 
lose their color and shrivel up, and on this account they are diffi- 
cult to detect in the mature seed. At germination, however, the 
chloroplasts again become active and assume their original form 
and color. 
SAcHS (1) states that the chloroplasts arise in the young cells 
by the separation of the protoplasm into portions which remain 
colorless and others which become green and sharply defined. . 
He holds that the process can take place by very small particles, 
originally of a different nature from the apparently homogeneous 
protoplasm in which they are distributed, collecting at definite 
places and appearing as separate masses. 
Botanical Gazette, vol. 5:] [378 
