THE ORIGIN OF ANGIOSPERMS. 31 
HISTORICAL. 
The great race of plants, commonly referred to as the * Flowering Plants," 
differ so obviously from the rest of the Vegetable Kingdom, that they were 
recognized, comparatively early in the history of botanical study, as forming a 
distinct group, and for a long time attention was almost entirely concentrated 
on them. 
The stamens and carpels were soon identified as the male and female organs 
respectively, and by the close of the 17th century Camerarius had shown 
that reproduction by means of seeds depends on the male element, 
the pollen, reaching the receptive part, or stigma, of the female organ ; 
though what exactly happens in the process of fertilization remained mere 
guesswork until many years later. This establishment of the sexual theory 
of reproduction in Flowering Plants led to the subdivision of the V egetable 
Kingdom, by Brongniart in 1843, into two great groups, the Phanerogams 
and the Cryptogams, the latter still being incorrectly regarded as devoid of 
sex, and as possessing a ‘cryptic’ type of reproduction. 
The researches of Robert Brown led to the distinction of Gymnosperms as 
opposed to Angiosperms, though for many years the former were commonly 
looked upon as a detached group or appendage of the Dicotyledons, with the 
consequence that the terminology of the flower came to be applied to their very 
different kind of fructification. Hofmeister’s classical researches, published 
in the years 1849 and 1851, completely broke down the barrier separating 
the Phanerogams from the Cryptogams ; in fact these terms were no longer 
applicable in their original sense, for their meaning had become reversed, 
since the Flowering Plant was found to be more ‘ cryptogamic’ as regards its 
manner of sexual reproduction than the Fern. The alternation of generations, 
so clear in the Pteridophytes, was shown to be also present in both Gymno- 
sperms and Angiosperms. The male and female prothalli of the heterosporous 
Vascular Cryptogams had their very reduced representatives in the pollen-grain 
and embryo-sac respectively of the Phanerogams. 
These discoveries, followed so closely by the publication of Darwin’s 
‘Origin of Species,’ gave a great impetus to the evolutionary hypothesis as 
applied to plants, and a great stimulus to phylogenetic speculations. 
Though the various parts of the embryo-sac of the Conifer could be 
interpreted in terms of the female prothallus of a heterosporous Pteridophyte, 
investigations of the corresponding organ of the true Flowering Plant (either 
Monocotyledon or Dicotyledon) failed to show any such clear homologies. 
In other words the gap that originally existed between the Phaneroga ms 
and Vascular Cryptogams was now bridged, and in its place there appeared 
a wide gulf between the Conifers and true Flowering Plants, or more exact ly 
between the Gymnosperms as a whole and the Angiosperms. 
