850 VITALITY OF SEEDS. 
days; while others, as certain of the Conifer, &c., require more 
than twelve months. 
4, Or THE SeED.—The structure and general characters of 
the seed, as well as the origin and progressive development of 
its parts, have been already fully alluded to in a former section ~ 
of this work (pages 333-348). 
Our limited space prevents us from alluding to the multitude 
of ways and contrivances by which the natural dissemination of 
seeds is effected, and to the number of seeds produced by 
plants. Suffice it to say that, in all cases, a great many more 
seeds are matured than are required for the propagation of the 
species ; and thus the extinction of the species in consequence 
of their decay, and their use for food by animals, &c., is pro- 
vided against. 
Vitality of Seeds.—Seeds vary very much as to the time 
during which they will preserve their power of germinating. 
This vitality is frequently lost long before they lose their value 
for food. Some seeds of an oily or mucilaginous nature, or which 
contain much tannic acid, speedily lose their vitality, and decay ; 
this is the case, for instance, with Nuts and Acorns, and hence, 
when seeds of this nature are required for propagation, they must 
be sown immediately or within a short time of their arriving at 
maturity, or special means must be adopted for their preserva- 
tion. Other seeds, such as those of a farinaceous nature, as 
Wheat and Cereal grains generally, or those with hard and bony 
integuments, as many of the Leguminose, frequently retain their 
vitality for years. 
From the experiments of De Candolle, those of a Committee of 
the British Association, and of others, it would appear gener- 
ally, that the seeds of the Leguminosz and Malvacez preserve 
their vitality longest, while those of Composite, Cruciferze, and 
Graminacez soon lose their germinating power. But some ex- 
ceptions to the above statement occur in these orders. 
Under particular circumstances it seems certain that seeds 
have preserved their vitality for a long period. Some of the 
cases brought forward as illustrations of this capability of seeds 
are, however, not supported by careful observations, as, for 
instance, that of the vitality of Wheat taken from Egyptian 
mummies. There are no well-authenticated instances of Wheat 
taken from mummies, which have been untampered with, germi- 
nating ; indeed, all experiments (Dietrich, Lardet, Haberlandt), 
tend to show that Wheat loses its power of germination in from 
three to seven years. But other well-authenticated instances of 
seeds having preserved their vitality for a lengthened period are 
on record. Thus, on the authority of Dr. Trimen, it was stated 
in the third edition of this Manual that some seeds of Nelwmbinm 
in the herbarium (now in the British Museum) of Sir Hans 
Sloane, who died in 1753, germinated in 1866 ; these must, there- 
fore, have been considerably over a century old. Mr. Kemp, 
