ALLEN— SEX INHERITANCE IN SPH.EROCARPOS. 293 



and 6 were sent from Austin, Texas, by Professor F. McAllister; 

 those shown in Figs. 7 and 8 were from cultures which began with 

 plants received from Professor R. S. Cocks, New Orleans, January 

 15, 1917, the drawings having been made in February, 1919. 



It must be noted, in considering the difit'erences in question, that 



Sphccrocarpos texanus. Living female (Fig. 5) and male (Fig. 6) plants 

 as found in nature. Received from Austin, Texas, February 13, 1919; dravirn 

 February 15, 1919. Drawings by Miss Martha Engel. X 7- 



in such characters as the size and form of the lateral lobes, size, 

 form, and closeness or distance apart of the involucres, and size of 

 orifice, there is great variation between individual plants in the cul- 

 tures, as well as evidently also in nature. Compare, for example. 

 Figs. 3 and 9, both representing female plants oi S. Donnellii from 

 greenhouse cultures, that shown in Fig. 9 bearing sporophytes. 

 Much of this variation is obviously due to environmental conditions, 

 but some of it apparently to the existence of differing strains of 

 sub-specific rank. 



The changes that appear under cultivation seem not to be corre- 

 lated with any loss of function on the part of the sex organs or of 

 the gametes. At any rate, it is easy, as already noted, to secure fer- 

 tilization, as a result of which sporophytes are formed in abundance, 

 especially in late winter and spring. At other seasons either fertili- 

 zation or sporophytic development seems to meet with more diffi- 

 culty, and the proportion of sporophytes obtained is ordinarily 

 smaller. 



