830 
MECHANICS OF GROWTH. 
The first point to determine is, whether germination — /. e. the growth of the embryo 
at the expense of the reserve materials in the seed — takes place only at certain tempera- 
tures, and at what temperature it takes place most quickly. Observations of my own 
gave the following results : — 
Inferior limit. Most rapid growth. Superior limit. 
5°G. 287° G. 42*5° G. 
5 , 287 377 
137 337 46-2 
9'5 337 46-2 
9'5 337 46-2 • 
Tr'iticum 'vulgare 
Hordeum imlgare 
Cucurbita Pepo 
Phaseolus multiflorus 
Zea Mais 
This table shows, if the ascertained temperatures are correct, that grains of Wheat 
cannot germinate below 5° G., or seeds of the Gourd below 137°, &c., however long they 
may lie in moist earth ; and that they no longer germinate, but quickly perish at tempera- 
tures above those named in the third column ; while at the temperatures named in the 
second column germination takes place in a shorter time than at either higher or lower 
temperatures. It may however be taken for granted, from the great difficulty of obtain- 
ing these numbers, that the result of further observations will not be identical, though 
probably approximate. It is clear that many series of experiments will be necessary 
in order to determine each of the cardinal points. The following figures, obtained by 
Koppen, agree moderately well with mine, as far as they relate to the same plants : — 
Triticum vulgare 
Zea Mais 
Lupinus albus 
Pisum sativum 
Inferior limit 
7-5° G. 
9-6 
7'5 
67 
Most rapid growth. 
297° G. 
32-4 
28-0 
26-6 
The following figures were obtained by H. de Vries :- 
Most rapid growth. 
Superior 
limit. 
Phaseolus vulgaris 
31-5° G. 
above 
42*5 
Helianthus annuus 
31*5 
below 
42-5 
Brassica Napus 
3i"5 
J? 
42-5 
Cannabis sativa 
3i'5 
above 
42-5 
Cucumis Melo 
37'5 
Sinapis alba 
27-4 
above 
37-2 
Lepidium sativum 
27-4 
below 
37*2 
Linum usitatissimum 
27'4 
above 
37*2 
The following results^, obtained byAlphonse de Candolle, are moderately trustworthy 
as far as relates to the inferior limit, but hardly so much so with respect to the superior 
limit and the temperature of most rapid growth, as may be concluded from various 
statements made by the observer. 
Inferior limit. 
Most rapid growth. 
Superior limit. 
Sinapis alba 
o-o° G. 
2I°G. 
28° G. 
Lepidium sativum 
rS 
21 
28 
Linum usitatissimum 
1-8 
21 
28 
Collomia coccinea 
5'o 
17 
about 28 ■ 
Nigella sativa 
57 
above 21 (?) 
„ 28 
Iberis amara 
57 
Trifolium repens 
57 
21-25 
below 28 
Zea Mais 
9-0 
21-28 
about 35^ 
Sesamum Orientale 
13*0 
25-28 
below 45 
^ I take the figures from the table of curves in De Candolle's treatise, with the assistance of 
the text. 
2 De Candolle remarks that the seeds of Maize, Melon, and Sesamum become brown, the first 
