62 The Different Modes of Origin of new Species. 
cultivated varieties are as old or even older than cultiva- 
tion itself. 
If we examine a number of such derived forms in any 
systematic work or flora, it immediately becomes evident 
that the same kind of differences recur in the most widely 
j 
separated families, genera and species. Everywhere vari- 
eties present series of parallel forms. The recurrence 
of white flowered varieties in numerous species with blue 
or red flowers is so familiar a phenomenon, that often 
all reference to them is omitted. LINNAEUS himself knew 
that nearly all such species had a white variety. If the 
color of a flower is compound, and if one of the compo- 
nents is lacking, a white flower with a dark center often 
results and is known as a ]\ir. bicolor (for example Cyno- 
(llossmn offieinale bicolor, Agrostenuua coronaria bicolor} ; 
or the dark patches are absent as in Geutiana piinctata 
concolor, which case is exactly analogous to that of Arum 
niacitlatuni iiiimacnlatinu. 
Often too, the clothing of hair is lacking either on 
the whole plant or, when only certain parts are densely 
hirsute in the "species," on these. The nomenclature of 
the series of parallel forms, under this heading, is par- 
ticularly rich in terms which all indicate the same prop- 
erty, as for example : Papaver dubium ylabrum, Biscn- 
tella laevigata glabra, Arabis ciliata ylabrata, Arabis hir- 
suta ylabcrrima, Veronica spicata nitens, Amyydalus Per- 
sica laciis, Eritrichium namun leiospermum, Paeonia 
corallina (pcrcyrina) leiocarpa, etc. 
Thornless forms are usually termed incnnis; they oc- 
cur in Ranunculus arvensis, Genista ycrmanica, Robinia 
Pseud-Acacia and many others. The ] T arietas ciliata 
occurs in Cytisus prostratus and in C. spinescens, also in 
Lotus corniculatus, etc. A dense clothing of hair is the 
