1888.] Mr M. C. Potter, Note on Seeds in the genus Iris. 305 
(5) Note on the Germination of the Seeds in the genus Iris. 
By M. C. Porter, M.A., Peterhouse. 
Ir is a well-known fact that some seeds germinate very soon 
after being planted, while others take some considerable time. 
This is very well marked in the seeds of the various species of 
Iris, the seeds of some species taking only a few weeks, those 
of other species requiring twelve or even more months to germi- 
nate. In order to try to discover the reason of this, seeds of 
various species were planted in ordinary flower-pots, and exposed 
to the same conditions of temperature and moisture, and the 
embryos examined frotn time to time. The embryos were taken 
from the seeds, the protoplasm fixed with picric, chromic and 
osmic acids, then cut and mounted in the usual way. 
When the seed is ready to be detached from the parent plant 
we find the embryo to be fully developed as regards its size and 
morphological differentiation, but unfit to germinate until im- 
portant changes have taken place in the nucleus and protoplasm 
of the cells. In this stage the cells of the embryo are densely 
filled with nucleus and protoplasm, but contain no vacuoles; but 
gradually, as the seed is getting ready to germinate, small bodies 
are formed in the protoplasm which increase in size, are numerous 
in each cell, and are found to consist of proteid matter. Each of 
these bodies is included in a vacuole. Each cell therefore now 
has its nucleus and protoplasm containing numerous vacuoles with 
their proteid bodies. These bodies disappear on germination, and 
hence, since different seeds take different lengths of time to 
effect these changes, they must necessarily germinate at different 
intervals of time. The species of Iris which germinate quickly 
perform these changes in a short space of time, while the long 
germinating ones take a considerable time. 
The Iris seeds are endospermous, with the embryo entirely 
enclosed in the endosperm, but the cells which immediately cover 
the radicle are few and form a kind of cap, which must be removed 
before germination. When germination commences the cotyledon 
elongates and pushes the radicle and plumule outside the seed to 
a greater or less distance, according to the nature of the soil, so 
that the most favourable place can be found; part of the cotyledon 
remains in the seed in order to transfer the contents of the endo- 
sperm to the young plant. The diameter of the hole in the 
endosperm through which the radicle is pushed always remains 
small in size, so that as the parts of the cotyledon on each side of 
it grow, a constriction is here formed in the cotyledon. 
In seeds which have the cells covering the radicle removed 
we find often the cotyledon much elongated, and, if the seed lies 
exposed or nearly so, becoming spirally twisted, so that the radicle 
may even be directed upwards and the free end of the cotyledon 
does not remain in close contact with the endosperm; hence the 
