RESEARCHES ON THE DEVELOPMENT OF STARCH-GRAINS, 803 
starch-forming-corpuscles increase considerably in size, the 
contained starch-grains undergo partial or complete absorp- 
tion, and at the same time a formation of pigment takes 
place. 
I will content myself with briefly describing a few 
instances. 
The conversion in question which accompanies the 
normal development of an organ appears to be of very 
general occurrence. The young leaves of Iris florentina 
contain no chlorophyll, but the parenchymatous cells which 
abut upon the fibrovascular bundles contain starch-grains 
which are attached to large starch-forming-corpuscles ; these 
portions of the leaves subsequently become green in conse- 
quence of the conversion of the starch-forming-corpuscles 
into chlorophyll-corpuscles. 
The behaviour of the starch-forming corpuscles in the 
tubers of Phajus grandifolius (figs. 42, 43) is very remark- 
able. The tuber is at first surrounded by a dense invest- 
ment of leaves, but, in consequenee of its growth, it gradu- 
ally emerges and the leaves die off. The tuber is at first 
quite white, but it soon turns bright green after exposure to 
light. Close observation shows that the starch-forming- 
corpuscles increase considerably in size, that the contained 
starch-grains are partially absorbed, and that they develope 
into rod-shaped chlorophyll-corpuscles ; bodies of this kind 
can be found especially well-developed in the bundle- 
‘sheaths of the upper parts of the tuber. Even when the 
starch-forming-corpuscle has been reduced to a small 
gelatinous residue, it becomes green in the manner de- 
scribed. In the external cells of the cortex only a partial 
conversion of the starch-forming-corpuscles takes place, and 
it is confined to that part of the corpuscle to which the 
starch-grain (which is in this case always very small) is 
attached ; it becomes a somewhat elongated chlorophy]ll- 
corpuscle, the starch-grain undergoing partial or complete 
absorption, which remains attached to the portion which has 
remained unaltered. In this way very curious bodies are 
formed, which Gris! has already observed in Phajus and 
Acanthephippium. 
In subterranean organs which are exposed to light the 
effect is the same. The outer cortical cells of the potato are 
especially instructive. The cells which lie immediately 
1 Gris, loc. cit., p. 195. I have never been able to observe the spherical 
bodies which he describes, in uninjured cells; but they always appear under 
the action of water. 
