290 



ALLEN— SEX INHERITANCE IN SPH^ROCARPOS. 



kept in healthy condition. In mixed cultures the female plants 

 crowd and choke out the males, which latter in such cultures are 

 sure sooner or later to disappear. As already indicated, I have 

 cultures (now purely female) which have been growing continu- 

 ously since the early months of 1916, the plants having multiplied 

 as a result of their branching and apical growth and of the death of 

 the older portions, as well as by regeneration which occurs freely 

 under a variety of conditions from the lateral lobes, from the body 

 of the thallus, and from the involucres. Sporophytes have been 

 formed and the spores scattered in some of the cultures, in w^hich 

 cultures therefore not all the individuals now living are the result 

 of the vegetative growth of those originally present. It is easy, how- 

 ever, to obviate this possibility, so that a culture (clon or pure line) 

 of any desired extent can be obtained which is known to have been 

 derived by vegetative means from a single gametophyte, or from 



Sphccrocarpos Donnellii. Living female (Fig. i) and male (Fig. 2) 

 plants. Received from Sanford, Florida, April 10, 1919; drawn April 15, 

 1919. A very small portion of the anterior end of each plant (the upper ends 

 in the figures) represents growth since transference to the greenhouse; other- 

 wise the plants are typical of those in nature. Drawings by Miss Martha 

 Engel. X 7- 



the germination of a single spore. ]My oldest male cultures date 

 from spores which were sown June 16, 1916, the plants derived 

 from which were transplanted and have been kept in culture since 

 March 10, 191 7. 



