1890. ] Botany. 579 
by complication of structure, the process of bringing distant particles 
of protoplasm together seems the leading end of many plants, If seeds 
fail the plant has failed. Perennial plants, and those that are easily 
propagated non-sexually, are less subject to the law of “union or 
death’’ that prevails among annuals and biennials. 
Reproduction by union among the lower forms of life is primarily to 
place the species out of the jeopardy that otherwise might follow un- 
toward circumstances, and also to facilitate its more thorough distribu- 
tion. When we arrive as high in the scale as the ferns we find that the 
union takes place once for all in the life of the fern plant, and that the 
direct and immediate result is not a spore, but a plant upon which the 
spores are afterwards borne annually in great numbers without further 
fertilization. Each spore in germination produces a small, delicate 
e of célls, the prothallus: one protoplasmic mass, the germ-cell of 
the archegonium, grows into a fern plant after it has been stimulated 
by the commingling with it of the male elements. Cases are on record 
where the fern plant has developed from the prothallus without the 
intervention of the antherozoids, but they are rare. A few plants may 
go on for many years producing crops of spores, but it is the rule that 
it. shall not begin this life of spore-bearing until a union has taken 
place. In the moss the union precedes the formation of each capsule, 
and each capsule bears a multitude of spores. For the same number of 
spores it is easy to see that fewer unions are required in the moss than 
in the pond scum, and more than in the fern. Although this union 
enters into the plan of reproduction, its influence is far-reaching. 
Only the mathematician can write the figures representing the number 
of spores produced by a tropical tree fern through its long existence. 
The moulds and low-water plants may rejuvenate by union upon 
seemingly the slightest provocation. In the moss it means much more 
than in the lower forms, and in the ferns it means infinitely more. As 
we pass beyond the cryptogams, and study the flowering plants, may 
` it not be safe to conclude that here, where the structures in the sexual 
apparatus are vastly more complicated than upon the prothallus, we 
have results that are correspondingly more lasting? It suffices for the 
banyan-tree, that covers many acres, and the impulse of fertilization 
lasts through the lifetime of the oldest trees, which is estimated to be 
not less than four thousand years. Every seed that falls from the giant 
red-wood has its spore in the vitality stimulated by the original union. 
If.this be not true, then we are forced to believe that the union was 
only serviceable, like the starch and oil in the cotyledons, for the initial 
growth of the seedling. Whatever view we take, the assumption holds 
