120 BOTANICAL GAZETTE [FEBRUARY 
species. Recently Howarp and Howarp,' in their excellent 
studies on Indian tobaccos, have isolated 51 types from the tobaccos 
grown in India, and have shown that these types remain constant 
even in minute and insignificant characteristics when propagated 
in pure line cultures. SHAMEL® also has found and repeatedly 
emphasized the fact that when seed is obtained from single self- 
fertilized mother plants, the progeny is entirely uniform. In one 
instance he reports that plants from Florida-grown Sumatra seed 
showed great variability for two generations when grown in Con- 
necticut, the seed being collected in the ordinary way from many 
plants, but when seed was saved from single mother plants in the 
second generation of northern grown plants the offspring of these 
plantswereuniform. The variability continued for two generations, 
but when seed was collected from isolated plants the environment 
had no further effect! 
Coox? found an exactly analagous behavior in cotton. When 
seed was saved from individual mother plants selected from the 
diverse forms of King cotton grown at San Antonio, Tex., the 
offspring of these forms were either uniform or showed definite types 
of variation. The occurrence of definite types of variation would 
seem to indicate that the parents were hybrids. 
It is scarcely believable in either the case of tobacco or of cotton 
that a single selection would destroy the plant’s capacity for being 
affected by its environment. In tobacco variation has been 
reported to persist at least during two generations in the new 
environment, yet from individual plants selected at any time a 
pure progeny was obtained. All such facts are more easily under- 
stood on the basis that the seed was derived from mixed parents. 
It is true, of course, that plants are modified in their fluctuating 
characteristics by changes in the environment, but so far as experi- 
mental evidence shows, such modifications persist only as long as 
the environment inducing them persists. Lr Cierc and Leavitt,’ 
s Howarp, A., and Howarp, G. L. C., Studies in Indian tobaccos. Mem. Dept. 
Agr. India (Bot. Ser.) 3:59-176. pls. 58. 1910. 
6 SHaMEL, A. D., loc. cil., Yearbook. 1904. 7 Cook, O. F., loc. cit. 
8Lxe Cuerc, J. A., and Leavrrt, S., Tri-local experiments on the influence of 
environment on the composition of wheat. U.S. Dept. Agr., Bur. Chem. Bull. 128. 
pp. 18. ro1o; rev. in Bot. GAz. 50153. Igto. 
