1903] Leavitt, — Drosera intermedia 267 
related to that which characterizes the leaf in the two remaining gen- 
era of Droseraceae, namely Dionaea and Aldrovanda. It is not an 
unusual, extreme, or highly specialized figure among leaf-forms in 
general. It prevails overwhelmingly in the genus Drosera, From 
it all the types in the genus are derivable. From a study of the 
specific forms and their distribution within the genus, accordingly, it 
seems easiest to regard the roundish leaf as primitive. 
The facts of geographical distribution point in the same direction. 
The 2. rotundifolia type, with the more broadly spatulate leaves, is 
cosmopolitan and is most widely distributed, whether we consider the 
whole group or individual species. Drosera rotundifolia, for exam- 
ple, encircles the globe in the northern hemisphere, and in latitude 
ranges from within the arctic circle to the southern United States. 
Drosera intermedia is hardly less widely spread. Other types, on 
the contrary, are in comparison much restricted geographically. 
Thus the peltate-leaved group is practically confined to Australia 
and vicinity, though one member has found its way across the 
islands to India. Similarly Drosera filiformis is confined to the 
Atlantic border of the United States from Massachusetts to Miss- 
issippi. An extension for the general type, however, is found within 
apparently somewhat narrow limits in Brazil. Generally speaking 
those forms which have the appearance of being the most specialized 
and least likely to represent the ancestral stock are geographically 
most restricted. In so far as any conclusion at all may be arrived 
at from this kind of evidence, it is that the fundamental form amongst 
the Sundews is that of the round-leaved, or roundish-leaved, kinds, 
and that the other forms have been derived from it. 
While the foregoing considerations, which necessarily lose some of 
their force from being much condensed, may not of themselves 
furnish a sure argument, they materially substantiate inferences 
drawn from a comparison of individual, or ontogenetic, development 
in several diverse species. 
As is well known, organic beings often have a marked qualitative 
as well as quantitative development after birth or germination. At 
the beginning of its independent career, oftentimes the plant mani- 
fests properties which it subsequently adds to or diminishes or 
entirely loses. In infancy qualities appear which seem to be natural 
to infancy alone. ‘These are later replaced by characters proper to 
approaching maturity. Finally the adult characteristics make their 
