VARIATION 317 
2. Environment conditions development of inherited characters.— 
(a) Light and metabolism. In a general sense light conditions life 
in all normally green plants. It certainly conditions normal develop- 
ment in such plants. Potatoes sprouted in a dark room develop no 
chlorophyll in the stems and the rudimentary leaves are abortive. 
In many bulbous plants, however, the influence of moisture and heat 
are sufficient to induce leaf growth and even development of the 
inflorescense, but it is all done at the expense of the food stored up in 
the bulbs. 
a b c ad e 
Fic. 55.—a, Typical wild pigeon, Scardafella inca; b, the form dialeucos; c, 
braziliensis; d, ridgwayi; e, inca after three moultings in a moist atmosphere. 
(After Beebe, from Babcock and Clausen.) 
b) Temperature and flower color. Baur reports an experiment with 
a red variety of the Chinese primrose, Primula sinensis rubra. Tf 
plants of this variety are raised by the usual method until about one 
week before time to bloom and then some of the plants are put in a 
warm room under partial shade (temperature from 30° to 35° C.) and 
the remainder in a cool house (temperature from 15° to 20° C.), when 
they bloom those in the warm temperature have pure white flowers 
while those in the cool temperature have the normal red color of the 
variety. Moreover, if plants are brought from the warm into the 
