184 ESSAYS. 
Or, in Termini Botanici, “ pagina superiore lateribus ap- 
proximatis ita ut alterum latus distinguat alterum folium.” 
This, as the definition and the diagram in the “ Philosophia 
Botanica” show, answers in estivation to mode II. It was 
early taken up as such by Mirbel (Elem. Phys. Veg. et Bot., 
1815, ii. 738, 739), where the polypetalous corolla of Her- 
mannia and Oxalis and the gamopetalous corolla of Apocynee 
are cited as examples. 
Valvate zxstivation, our mode III, is rightly defined by 
Mirbel in the same place, and still earlier by Brown. 
Linnzus made no use of estivation as a character. Nor 
did Jussieu, except merely that, in his ‘“ Genera Plantarum,” 
the petals of Malvaviscus are said to be convolute. 
In De Candolle’s ** Théorié Elémentaire,” 1813 —a still 
unsurpassed treatise, upon which, next to the “ Philosophia 
Botanica,” our botanical glossology rests — neither the word 
estivation, nor its synonym, prefloration, is mentioned, and 
even vernation or prefoliation is equally omitted. 
But the history of zstivation as a botanical character be- 
gan in a work published three years earlier, namely, in R. 
Brown’s “ Prodromus Flore Nove Hollandiz,”’ 1810. The 
preface notes that it was first accurately observed by Grew. 
In it Brown defines only the valvate mode, “ubi margines 
foliolorum vel laciniarum integumenti invicem applicati sunt, 
capsule valvularum in modum.” In the body of the work, 
wherever it is important, the zstivation is noted as valvate, 
imbricate, plicate, induplicate, ete.; and the open stivation 
(aperta) is named by him in a subsequent paper. 
Being the first to employ zstivation systematically, and to 
develop its value, Brown’s terminology for its modes may well 
be considered authoritative. And so indeed it is, as far as it 
goes. But he did not make one important distinction, namely, 
that between our I and II. Imbricate, in his use, comprises 
all kinds of overlapping, that of the corolla of Apocynec and 
of a Gentian, as well as that of a Primrose. He must have 
not only noticed the difference, but also appreciated its gen- 
eral importance, notwithstanding the occasional passage of 
the one into the other. He must have also observed that in 
