478 CHARLES ROBERT DARWIN. ~ 
to the single instance in which they took the same subject in hand. 
In his papers on the organs and modes of fecundation in Orchidex 
and Asclepiadee, Mr. Brown refers more than once to C. K. 
Sprengel’s almost forgotten work, shows how the structure of the 
flowers in these orders largely requires the agency of insects for 
their fecundation, and is aware that “in Asclepides . .. the in- 
sect so readily passes from one corolla to another that it not u- 
frequently visits every flower of the umbel.” He must also have 
contemplated the transport of pollen from plant to plant by wind — 
and insects ; and we know from another source that he looked upon — 
Sprengel’s ideas as far from fantastic. Yet instead of taking the - 
single forward step which now seems so obvious, he even hazarded — 
the conjecture that the insect-forms of some Orchideous flowers — 
are intended to deter rather than to attract insects. And so thè 
explanation of all these and other extraordinary structures, 38 _ 
well as of the arrangement of blossoms in general, and even the i 
very meaning and need of sexual propagation, were left to be ee, 
plied by Mr. Darwin. The aphorism ‘‘ Nature abbors a vacuum — 
is a characteristic specimen of the science of the Middle Age — 
The aphorism “ Nature abhors close fertilization,” and the demor- — 
stration of the principle, belong to our age, and to Mr. Dari 
To have originated this, and also the principle of Natural 3 
lection—the truthfulness and importance of which are evident 
the moment it is apprehended—and to have applied these 
within a dozen years, a deeper impression upon natural history 
than has been made since Linneus, are ample title for one 
fame. eo 
There is no need of our giving any account or of estimating the 
importance of such works as the ‘+ Origin of Species by a 
Natural Selection,” the “Variation of Animals and Plants ™ 
Domestication,” the “Descent of Man, and Selection in rel ee 
to Sex,” and the ‘Expression of the Emotions in Man and x 
imals,”— a series to which we may hope other volumes ma, 
time be added. We would rather, if space permitted, T 
_ analysis of the less known, but not less masterly, subsidiary 
upon the various arrangements for ensuring cross-fertiiZ® es 
flowers, for the climbing of plants and the like. These 
have heard, may before long be reprinted in a volume, and 5 
. 
mented by some long-pending but still unfinished it 
