1895.] Deviation in Development Due to the use of Unripe Seeds. 811 
To fully understand the problem before us it will be well to 
inquire into the meaning of maturity. In the course of nor- 
mal development of the seed the testa becomes more firm and 
less permeable, the organic constituents of the cells are trans- 
formed into solids or semi-solids, there is a loss of water, growth 
finally ceases, the organic connection with the parent plant is 
severed, and the seed is ripe. It remains in an inactive, dor- 
mant condition a longer or shorter time and then germinates. 
Maturity is reached in this metamorphosis when the protect- 
ing testa, or pericarp, as the case may be, has become suff- 
ciently solid, and the inner parts sufficiently advanced to per- 
mit separation from the parent plant without endangering the 
life of the embryo. 
A most curious thing in connection herewith is the fact that 
the seed, and sometimes the associated parts of the fruit, will 
continue to develop under circumstances which put a stop to 
all growth in the vegetative parts of the plant. Ifa branch is 
severed from a tree, all growth in its buds and leaves ceases at 
once, it wilts, and shortly dies. But the fruits and seeds at- 
tached to it continue to develop, and will so continue as long 
as sufficient moisture remains to transport what food material 
exists, from the leaves and stem into the fruit and seed. This 
process is known as after-ripening. So far as I know, it has 
not been intimately investigated, but I am inclined to think 
that during this process the embryo continues in actual growth, 
forming new cells, and elaborating its organs, but that little or 
no growth takes place in the surrounding parts, although great 
chemical changes and accumulation of substances do oceur. 
It was observed by Cohn,” who was the first to note such 
phenomena, that green seeds entirely removed from the fruit 
and laid in moist earth or sand passed through the various 
changes of color of normal ripening. If very young, they did 
not progress far, but if sufficiently grown, although still per- 
fectly green in color, they underwent the intermediate changes, 
and finally gave every appearance of full, mature seeds. He 
experimented with the seeds of apple, pear, beans, lupines, 
Amarantus caudatus, Polygonum tartaricum, Colutea arbor- 
2 Symbola, pp. 67-70; Flora, pp. 508-510. 
p 
