Presidents Address lxxv 
called instinct, it is something very similar to it. Hence, it might 
appear that the plants are generally at a great disadvantage in com- 
parison with the animals, being fixed to the spot on which they begin 
their life, while the animals are at liberty to move about and occupy 
the regions that suit them best. There is, however, one important 
faculty possessed by plants, which does not only balance this draw- 
back, but often accords them a considerable advantage over the animals, 
namely, their power of spreading their progeny over wide areas before 
they settle at a permanent spot for the entire length of their existence. 
While broad rivers or high mountains effectively block the way for 
many animals, while the inhabitants of a swamp or lake are generally 
unable to cross the dry region that separates them from another similar 
locality, such obstacles are easily overcome by the seeds of many plants. 
If the latter did not possess the means of dissemination, and their off- 
spring were consequently to germinate in close proximity to the parents, 
it would lead to a deadly competition between the individuals most 
similar to each other ; it would favour close fertilization, and weaken the 
reproductive power of the species, and it would further endanger its 
existence by restricting it to a limited area, which local changes may 
render unfit for it, while many other suitable localities would remain 
unoccupied. Effective arrangements for securing the spreading of its 
seeds are consequently one of the most necessary outfits of a plant in 
the general struggle for existence, and although hundreds or thousands 
of its seeds may be carried to unsuitable localities, the others that do 
succeed in reaching a congenial spot are more than sufficient to propa- 
gate its kind. What does it matter if even 99 per cent. of the seeds of 
an orchid or of a heath are carried to localities not fit for them when a 
single plant produces thousands or millions of seeds every year? The 
object is secured, although it may appear to us by wasteful means. 
The contrivances for securing this object are manifold, although the 
agents which act as auxiliaries to the plants are only small in number. 
These agencies are the wind, water, and animals, and sometimes the 
contraction of certain tissues of the fruits. Seeds are adapted to dis- 
tribution by the wind either by their smallness and lightness or by 
appendages. Small seeds that are easily carried away by wind of 
moderate strength are of common occurrence in several orders largely 
represented in South Africa, ¢.g., Scrophularinee, Crassulacee, Cam- 
panulaceze, Lobeliacew, and many genera of other orders. 
It is specially noteworthy that the capsules containing these seeds do 
not drop them all at once, but opening gradually, they allow the seeds 
to depart one by one whenever the seed-vessels are sufficiently shaken 
by the wind. One may hear the seeds rattle in the dry capsules of 
many of these plants, one of them (Montinia acris) having been sur- 
