ALLEN— SEX INHERITANCE IN SPH.EROCARPOS. 291 



C. and R. Douin (1917) report having kept female plants of S. 

 tcrrcstris (=^. Micheiii Bell.) and ^. caUfornicns {=S. texanus 

 Aust.) in cultivation for nine or ten months, and conclude that the 

 female thalli " may live indefinitely at a suitable humidity." The 

 male thalli, however, they say, are much less resistant and " dis- 

 appear little by little in the presence of humidity." Campbell 

 (1896) has noted the appearance of Sphcerocarpos plants (appar- 

 ently of both sexes) in a culture of other liverworts grown under 

 glass, and Goebel (1907) describes a culture of female plants which 

 had grown vigorously for two years. So far as I know, these are 

 the only previously published accounts of Sphcerocarpos in culture. 

 In my own work, best results have been obtained by growing the 

 plants in pots containing a mixture of about equal parts of clay loam 

 and sand. The pots stand on earthenware plates or enameled metal 

 pans in a Wardian case ; a little water is kept in the plates or pans. 

 The soil in the pots is thus constantly moistened from below. Un- 

 der these conditions contamination of the cultures by other organ- 

 isms is kept at a minimum, though of course by no means entirely 

 prevented ; and, even in case plants of both sexes are growing in 

 the same pot, fertilization does not occur. Fertilization can be 

 brought about when desired by flooding from above with sterilized 

 water, a pot containing male and female thalli. The plants must be 

 transplanted occasionally, both to relieve overcrowding and to free 

 the cultures from contamination, especially by blue-green algae, 

 which are the greatest source of trouble. The only other weeds 

 that cause serious annoyance are mosses, and they are not difficult 

 of exclusion when a culture is once free from them. 



Campbell (1896) and C. and R. Douin (1917) have noted that 

 Sphcerocarpos under greenhouse conditions takes on a form notice- 

 ably dififerent from that which it exhibits in nature. Campbell's 

 plants were either (or both) those of S. caUfornicns Aust., which 

 Miss Haynes (1910) and the Douins agree is identical with 6". 

 texanus Aust., or of 6^. cristatus, a California species later separated 

 and described by Howe (1899). The Douins' statements apply to 

 both S. Micheiii Bell, and S. texanus. 



The observations of these authors are confirmed by my own on 

 S. DonnelUi. Figs, i and 2 represent female and male plants, re- 



