394 = J. C. Draper—Hwolution of Structure in Seedlings. 
The hours selected were 7 A. M. and 7 P.M. I thus obtained 
the night and day, or dark and light growth of every seedling, 
as long as those in the dark grew. The seeds were planted on 
June lst, and appeared above the ground on June 6th, when 
the measurements were commenced. In each series one see 
failed to germinate; the record consequently is for four plants 
in each, and the history of the evolution of structures is as 
follows : 
Evolution of structure in the dark.—In Table I. the seeds are 
designated as A, B, C, D, and each column shows the date on 
which leaves and lateral growths appeared. These constitute 
periods in the development of the plants, which are indicated by 
the numbers 1, 2, 3, 4, 5, 6. The weight of each seed is given 
in milligrammes. 
Table L—Seedlings grown in the dark. 
A. B, Cc. 
Weight of seed. 43i. 436. 456. 500. 
Period 1, wth day. 7th day. 7th day. 7th day. 
s“ 2, 8th “ 9th “ 9th “ sth “ 
“ 3, 10th “ 10th “ llth “ 10th “ 
ee 12th “ 12th “ 13th “ 12th “ 
ee 14th “ 15th “ 15th “ 14th “ 
ech 17th “ isth “ 18th “ 17th “ 
, A glance at the above shows the uniformity as regards time 
with which the structures were evolved in each plant. It also 
indicates for each plant. an equality in the number of perl 
of evolution, viz., 6, notwithstanding the difference 1m the 
weights of the seeds; and suggests that the power of evolution 
of structure in seedlings resides in the germ alone. 
The character of the evolution in the six periods shows 4 
steady improvement or progression. 
In the first, the growth consists of the formation close to the 
stem of two partially developed pale yellow leaves. 
The second period is similar to the first, except that the 
leaves are a iitte teres 
The third presents a pair of small yellow leaves close to the 
main stem, from between which a lateral stem or twig ree 
hich @ 
and the tendril three times as long asin the third. 
The fifth is like the fourth, except that the tendril bifurcates- 
The sixth is similar to the fifth, except that the tendril trifur 
eates. 
_ Stem, leaves, twigs, tendrils of various degrees of complexity, 
all are evolved by the force pre-existing. bs the germ without 
