Black . — The Morphology of Riccia Frostii , A test. 527 
granule could not be shown to be the Anlage of the blepharoplast except for 
its position, for with the completion of the diagonal division it seems 
to disappear, and in an angle of the sperm cell there arises a more definite 
body which becomes the blepharoplast. 
Summary. 
1. The thallus of Riccia Frostii , Aust., is dioecious. Growth by means 
of apical cells results in a circular thallus or rosette attached to the ground 
by simple rhizoids. 
2. The air-chambers originate by the upward growth of adjacent ' 
filaments surrounding a depression at their junction. They are of various 
sizes. The mature air-chamber consists of a long, canal-like space separated 
by plates of chlorophyll-bearing tissue, one cell in thickness. 
3. Sexual organs are produced early, and continue to be produced with 
the development of the thallus. There is no definite grouping of the 
reproductive organs. The development of the reproductive organs is 
similar to that of other species of Riccia . 
4. The resting nucleus of the spore mother-cell contains a large 
nucleolus surrounded by a very fine network. The nucleus in the successive 
mitoses gradually decreases in size. No centrosomes or centrospheres are 
found in dividing spore mother-cells. 
5. The spore contains a very small nucleus, surrounded by food 
material, largely in the form of oil. Two protective coverings are developed, 
due to the activity of the protoplast. The endospore is formed later. The 
sculpturing of the outer coat consists of an irregular system of ridges. 
6 . The last division in spermogenous tissue is placed diagonally in the 
cell, and is sometimes accompanied by granules at the poles. No cell-wall 
was found between the resulting triangular walls. 
7. The blepharoplast is first distinguished in an angle of the cell 
as a sharply differentiated part of the cytoplasm. No evidence was found 
that showed the origin of the blepharoplast to be the polar granule in the 
preceding mitosis. 
8. In the developing sperm the blepharoplast elongates as a cord. 
The nucleus assumes a crescent shape and becomes homogeneous. The 
cord-like blepharoplast becomes closely applied to the nucleus, extending 
from it as a narrow thread, terminating in a conspicuously thickened part or 
head from which two cilia are produced. 
9. The mature sperm consists of a homogeneous nuclear portion, the 
transformed nucleus of the sperm cell, and the cytoplasm represented by 
a blepharoplast terminating in a head and bearing two cilia. A small amount 
of cytoplasm may persist as a vesicle. 
