216 BOTANICAL GAZETTE [MARCH 
grown in an entirely different environment. Sex goes beyond the 
organized visible structure of the protoplasm, and is probably 
bound up with the atomic or molecular structure, or dependent on 
some physical state which is reversible in most cells. It seems 
impossible to explain the known facts of sexuality and sexual 
morphology by any activities or movements of the larger structural 
units of the protoplast, such as chromosomes, chromatin granules, 
centrosomes, nucleoli, chondriosomes, etc. 
The geneticist must give as much attention to the expression 
of heredity as to the analysis of hereditary factors, and it is becom- 
ing more and more apparent that the environment plays a very 
prominent part in such expression, the characteristics of the 
individual being decidedly different when developed under one 
environment from what they would be if developed under another. 
So far as sexuality is concerned, the cells may be in such a state 
of equilibrium that closely associated groups may be thrown into 
the opposite sexual state and be differentiated as such simply 
because the one area is at a different metabolic level from the 
other. It is a common occurrence, therefore, not only in hemp 
but in great numbers of species, for sporophylls to be micro- 
sporangiate in one part and megasporangiate in another, or to 
have the characters peculiar to maleness in one part and those 
peculiar to femaleness in the other. 
Hemp is recommended as perhaps the most convenient plant 
to grow for experimental purposes, for classes in genetics, and to 
illustrate confusion of sexual expression and sex reversal. The 
_ flowers appear in from 30 to 36 days if planted about December 10, 
and the staminate plants can mostly be studied before it is neces- 
sary to pay attention to the carpellate individuals. The extreme 
dimorphism, the lack of vestigial parts in the normal flowers of 
the opposite set of sporophylls, the response in size of the plant at 
various seasons, and other peculiarities combine to make hemp of 
unusual interest to the student. 
The writer is under obligations to Mrs. BAYARD TAYLOR for 
much assistance in the work on plots 8,9, 13, and 14; andto Mr. 
R. J. Sum for assistance in the illustrations. 
