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IOWA ACADEMY OF SCIENCE Vol. XXIV, 1917 
SUMMARY. 
1. Blasia pusilla is a relatively simple liverwort having a 
dorsi-ventral thallus with laterally inserted leaf-like lobes. 
2. The growth of the thallus proceeds by means of the wedge- 
shaped apical cell, characteristic of the dichotomously branched 
forms. 
3. The thallus shows distinct strands of thick-walled cells 
functioning as mechanical and conducting tissue. 
4. The conducting strand is composed of elongate cells, ta- 
pering to a point at each end, and having pits scattered irregu- 
larly in the thick walls. 
5. Mucilage hairs are found on both sides of the thallus 
massed at the apex for the protection of the growing region. 
6. Rhizoids and scalelike amphigastria are found on the ven- 
tral surface of the thalli. 
7. The leaf auricles also found on the ventral surface are 
filled with Nostoc colonies. 
8. Blasia is dioecious, the antheridial plants being more slen- 
der and more deeply lobed than the archegpnial plants. 
9. Antheridia are found in two rows, one on either side of 
the midrib. 
10. Ten or twelve archegonia are formed near the apex of 
the plant, the group surrounded by the upstanding side leaves. 
11. Both archegonia and antheridia arise from dorsal seg- 
ments of the apical cell, and the initials are similar. 
12. Vegetative reproductive bodies or gemmae are developed 
in cupules on the dorsal surface of the thallus. 
13. These cupules have long tubelike necks from which the 
gemmae are forced by the swelling of mucilage in the base of the 
flask. 
14. The gemmae of Blasia are multicellular, each cell contain- 
ing a large nucleus and many oil globules. 
15. The gametophyte of Blasia pusilla occupies an interme- 
diate position between the thallose and foliose forms of liver- 
worts. 
16. This study shows that the cupules of Blasia, which are 
the most complex of the liverworts, are comparable to the 
simpler ones of Marchantia and Lunularia. 
Department of Botany, 
The State University. 
