Examples of Constant Races. 83 
constant varieties, based on data given by gardeners and 
botanists as well as on his own observations. 1 
It is a common opinion amongst gardeners that white 
flowered varieties are among the most constant. They 
are very plentiful and easy to control. From the cases 
as yet investigated it may be assumed that hybrids be- 
tween them and the colored species will be colored also, 
and therefore soon and easily discovered ; so that in the 
purification or fixation of these varieties the hybrids 
are usually removed soon and altogether, which is a 
very important thing for approaching constancy. Sev- 
eral investigators have tested the purity of white vari- 
eties. For instance HiLDEBRAND 2 worked with white 
Hyacinths, Delphinium Consolida, Matthiola incana and 
Lathyrus odoratus', HOFFMANN with Linnm usitatissi- 
11111111 album ; 3 HOFMEISTER for thirty years with Digitalis 
parviflora alba ; 4 PREHN with Scabiosa alba? etc. 
I myself have made similar observations. I started 
by buying a few plants of each of some varieties of 
perennial species, allowing them to flower on isolated 
spots and then saving and sowing their seed. Wherever 
the isolation was complete all the offspring, with a single 
exception (Aquilegia chrysantha), were white flowered. 
The following were the species tested in this way (I give 
in parentheses after each one the number of plants which 
were raised from their seed and observed in flower) : Cam- 
pan ula pyram idalis alba (26), C. persicifolia alba ( 1 044 ) , 
1 IRWIN LYNCH, The Evolution of Plants, Journ. Roy. Hort. Soc., 
Vol. XXV, Pt. i, pp. 34-37, Nov. 1900. 
2 HILDEBRAND, Die Farbcn der Bliitlicn, p. 7p. 
3 HOFFMANN, Botan. Zeitung, 1876, p. 566. See also the very 
complete list of constant white varieties given by CARRIERE, pp. 12-13, 
and the literature cited there. 
4 HOFMEISTER, Allgemeine Morphologic, p. 556. 
5 J. PREHN, Schr. Naturw. Vereins Hoist ein, Vol. X, 1895, p. 259. 
