102 JOHN H. SCHAFFNER Vol. XXII, No. 4 



If sexuality is a pltysiological state of the cells, then it 

 becomes evident that sex reversal might take place at any 

 time and in any cell or tissue. A neutral condition may change 

 to a male state or to a female state, or one sexual state may 

 give place to the other, or a sexual state may revert to a 

 neutral state again. Such reversals not only take place nat- 

 urally in hermaphroditic, bisporangiate, monecious and mono- 

 sporangiate individuals, but they can be induced in various 

 ways by artificial means in diecious sporophytes, as has been 

 done by the writer and others in Cannabis saliva, Hitmidus 

 japonicus, Ariscema triphyllum, and Ariscema dracontiiim. 



If a distinction is to be made between different categories 

 of sexual characters, then in order to avoid confusion of ideas 

 and improper deductions, the terms "primary" and "sec- 

 ondary" need a more exact definition for application in genetics 

 than they have received heretofore. 



The proper place to draw the line is between gametes on the 

 one hand and all other cells on the other. The ordinary dimor- 

 phic characters are produced because of the presence of a sexual 

 state and not because of differences in heredity of the cells 

 involved. A primary sexual character is, therefore, defined as 

 any sexual character possessed by a gamete. A secondary 

 sexual character is any sexual character possessed by any cell, 

 tissue, or organ other than a gamete. Thus the wall cells and 

 stalks of spermaries and ovaries may show secondary sexual 

 characters comparable to those of cells farther away in the 

 vegetative body. The main differences in primary sexual 

 characters pertain to the size and shape of the gametes, size of 

 or presence and absence of flagella, differences in activity, dif- 

 ferences in food contents, and differences in color. The funda- 

 mental differences exhibited between eggs and sperms are 

 often quite uniform throughout a class or phylum, while "sec- 

 ondary sexual characters may be quite diverse. 



The lowest plants are apparently devoid of sexual states 

 during their entire life cycle, and the first indications of sex 

 are entirely physiological. Passing on from this condition of a 

 physiological state, the first appearance of a structural difference 

 or dimorphism appears in the gametes. These differences soon 

 reach a general, normal, dimorphic condition in the Gonidi- 

 ophyta with well-differentiated eggs and sperms. So long as 

 organisms are unicellular they cannot be described as her- 



