808 The American Naturalist. [September,. 
Wiesner” has given a concise definition. “The condition,” he 
says, “in which a seed loosens itself from the plant in order to 
continue its development independently, is designated as ma- 
turity.” We are, therefore, to regard maturity as applying to 
the seed as a whole, and viability as applying to the embryo, 
the physiological processes associated therewith being quite 
distinct. After-ripening, which takes place when partly grown 
seed is separated from the parent plant, only leads to partial 
maturity. : 
It is an inquiry full of interest as to the minimum develop- 
ment at which a seed will germinate. Goff, in 1884, planted 
tomato seed in March in boxes in the greenhouse, saved the 
previous season from fruit still thoroughly green, and obtained 
only 2 per cent of vegetation. But seed from fruit of full size, 
and which had begun to lose its green color, although not yet 
showing any tinge of redness, vegetated 84 per cent, while from 
fruit with a faint reddish tinge the percentage of vegetation 
reached 100. In another experiment he found” that peas 
planted in the usual manner in the open ground in April, that 
had been gathered when in the condition best suited to table 
use, gave only 3 per cent of vegetation, while those just past. 
this stage of edible maturity gave 9 per cent. But inall prob- 
ability the conditions of growth at the time were not particu- 
larly favorable, as fully ripe seed in the same experiment gave 
only 54 per cent. of vegetation. In a very carefully conducted 
experiment with wheat made by Nowacki, selected seed saved 
from grain when in the milk gave 92 per cent of vegetation, 
and from grain when turning yellow, as well as when fully 
ripe, gave 100 per cent., the seed being sown in the open 
ground (see table III.) Nobbe” found that seed of Spruce 
(Picea vulgaris Lk.) gathered on the first and fifteenth of each 
month from the middle of July to the first of November, and 
tested in the laboratory in the following January, gave increased 
“ Der Zustand, in welchem ein Same sich von der Pflanze loslést, um sich 
selbstiindig weiterzuentwickeln, wird als Reife bezeichnet. Wiesner, Biologie der 
Pflanzen, 1889, p. 40. 
"Lc, Hi, p. 224. 
Bis, ai, p- 232. 
»L G 
