. 294 
AMERICAN JOURNAL OF BOTANY 
[Vol. 9. 
Summary 
1. The male receptacle of Rehoulia hemisphaerica occupies a dorsal 
position, as a rule, posterior to the female receptacle which terminates the 
branch. 
2. The receptacle is usually more or less lunate in outline, although it 
may be circular, or more or less irregular. It is sessile, as a rule, although 
in rare cases it may be elevated on a very short stalk. 
3. R. hemisphaerica is monoecious, with the sex organs in distinct groups, 
although bisexual receptacles may occur. 
4. The antheridia show a tendency toward centrifugal development. 
Variations from the usual marchantiaceous type of development occur, 
such as the occasional appearance of an apical cell with two cutting faces 
and the occasional formation of only two primary spermatogenous cells 
in a segment. 
5. The male receptacle is a plastic structure, probably representing an 
elementary stage of a branch system and showing transitions from the 
''dorsal outgrowth" type to the "composite branch-system" type. 
Juniata College, 
Huntingdon, Pennsylvania 
LITERATURE CITED 
1. Bischoff, G. W. Bemerkungen iiber die Lebermoose, vorziiglich aus den Gruppen der 
Marchantieen und Riccien. Acta Acad. Caes. Leop. IT : 908-1088, pis. 67-71. 1835. 
2. Boulay, N. Muscinees de la France 11. Hepatiqiies. (Cited by Douin.) 
3. Campbell, D. H. Mosses and ferns. 3d ed. New York, 191 8. 
4. Cavers, F. Explosive discharge of antherozoids in Hepaticae. Torreya 3 : 179-182. 
1903. 
5. . On the structure and biology of Fegatella conica. Annals of Bot. 18 : 87-120, 
figs. 28-32, pis. 6, 7. 1904. 
6. . Contributions to the biology of the Hepaticae. Part I. Targionia, Reboulia, 
Preissia, Monoclea, pp. 47, figs. 1-12. Leeds and London, 1904. 
7. . Notes on Yorkshire Bryophytes IIL Rehoulia hemisphaerica (L.) Raddi. 
Reprint from The Naturalist, pp. 15, pi. 8, figs. 2-6. 1904. 
8. . Interrelationships of the Bryophytes. New Phytol. reprint no. 4, pp. 203, figs. 
1-72. 1911. 
9. Cutting, E. M. On androgynous receptacles in Marchantia. Annals of Bot. 24 : 349- 
357. 1910. 
10. Douin, C, and Douin, R. Le Reboulia Raddi. Rev. Gen. Bot. 30 : 129-145, figs. 
1-5. 1918. 
11. Dupler, A. W. The air chambers of i?e&0M/ia hemisphaerica. Bull. Torrey Bot. Club 
48: 241-252, figs. 1-22. 1921. 
12. Ernst, A. tiber androgyne Inflorescenzen bei Dumortiera. Ber. Deutsch. Bot. Ges_ 
25 : 455-464. Pl- 13- 1906. 
13. Evans, A. W. The genus Plagiochasma and its North American species. Bull. Tor- 
rey Bot. Club 42 : 250-308, figs. 1-8. 1915. 
14. Goebel, K. Archegoniatenstudien XI 11. Monoselenium tenerum. Flora loi : 43- 
97, figs. 1-45. 1910. 
15. . Organographie der Pflanzen IL Spezielle Organographie i. Bryophyten. 
Jena, 191 5. 
