DR. M. T. MASTERS ON THE PASSIFLORACEZÆ, 619 
AFFINITIES OF THE GROUP. 
The Passifloraceæ have been variously allocated by different authors. A. L. de Jus- 
sieu placed them near Cucurbits and Loasads—a position also assigned to them by 
Linnæus, the elder De Candolle, Agardh, Bentham and Hooker, and others. St.-Hilaire 
grouped them near to Loasads. The balance of opinion, indeed, seems to be in this direc- 
tion. Du Petit Thouars placed them near Violacee, in which disposition he was followed : 
by Lindley, who included them in his Violal Alliance. Adanson and Lamarck ranged 
them near to Capparids, Salisbury to Samyds. Others have pointed out their relation to 
Bixads and Resedas. Brongniart grouped them between Saxifrages and Hamamelids. 
Agardh has even suggested a resemblance to Bignoniads (Cobæa), but one which seems 
very remote. 
Hence it will be seen that while some authors include the order among Perigynous 
Exogens, others rank it amongst the Hypogynous group, thereby laying greater stress on 
the one-celled ovary and parietal placentation, characters possessed for the most part by 
the orders above named, than on the superior or inferior condition of the ovary, or on the 
point of emergence of the sepals, petals, and stamens, even though these latter charac- . 
teristics form the landmarks by which the main subdivisions of Exogens are known. 
In estimating the affinities of Passifloracee (as of other groups), the characters upon 
which we found our estimate must be regarded from various points of view. 
1. Numerical importance.—In the first place we have characters derived from the 
relative frequency of occurrence (in the orders under consideration) of a particular form 
or of a particular arrangement of organs. Such characters formed the basis of Adanson's 
system of classification*. They have the great advantage of being easily estimated ; 
nevertheless it has been well objected that they are of little value unless associated with 
other points, such as invariability, physiological importance, and the like. To some 
extent, however, such an association must, from the nature of things, be a necessary 
eoincidence. 
In illustration of my meaning, I will take those families which have been considered 
by various authorities to be more or less nearly related to Passifloraceæ, excluding 
those in which the relationship seems very remote, and taking no heed of the exceptional 
forms which occur. These families are sixteen in number. In the next place I will 
enumerate the most striking structural characters of Passifloracee, and will indicate, 
by means of numbers, the relative frequency of occurrence of these characters in the 
orders under consideration. Thus, suppose we take the most prominent characters, 
and those which are almost universally present in true Passifloraceæ, and disregard the 
few exceptional cases, it will be seen that Turnerads agree with Passion-flowers in the 
possession of twelve of those characters, and differ from them in the absence of the 
remaining four. Cucurbits have seven points in common with Passion-flowers, and nine 
points of difference, and so on. 'This numerical relation between the several orders may 
be more fully shown as follows :— 
* Adanson, Familles des Plantes. Paris, 1763. 
