MORPHOLOGY OP BLASIA PUSILLA 
437 
do the mucilage hairs. That Nostoc is absolutely necessary to 
the growth of Blasia, has not been ascertained, but it is true 
that small colonies are found in the young tlialli very soon after 
the germination of the gemmae. 
The dorsal differentiations include the sex organs, the calyptra, 
and the cupules, in which the asexual reproductive bodies are 
produced. 
CUPULES. VEGETATUVE PROPAGATION. 
Asexual or vegetative reproduction in Blasia pusilla is accom- 
plished in two different ways. The amphigastria or underleaves 
may become detached from the lower surface of the thallus and 
give rise to new plants. These scales are loosely attached, easily 
removed and well prepared to launch new thalli. The second 
method is by means of asexual bodies called gemmae, which grow 
in special receptacles on the thallus and upon being expelled 
give rise to new plants. 
The development of the cupule in which these gemmae are 
formed is extremely interesting. The initial of the cupule is a 
dorsal segment of the apical cell and the mature cupule is located 
rather near the apex of the plant. By repeated divisions vertical 
to the plane of the thallus, the dorsal segment gives rise to a com- 
pact cluster of cells just back of the growing point (5, figure 
86). Activity appears then to be retarded in this region and 
increased in the surrounding cells for they soon bulge up around 
the compact region, forming a rim (6, figure 86). Cell division 
is more rapid in the posterior part of the depression. 
The development of the cupule of Blasia follows closely the 
first few stages in the development of the Marchantia cupule 
as given by Barnes and Land. 1 Here is the same compact tissue 
whose cells fail to divide and thus allow the surrounding cells 
to outgrow them. According to Barnes and Land, 1 “In Mar- 
chantia the upgrowth of cells at the rim of the depression be- 
gins on the posterior margin but later extends completely around 
the depression, so that at maturity the cup is circular and of 
almost equal height on all sides. The origin of the cupule of 
Lunularia, has been shown to be the same as that of Marchantia, 
except that the development of the rim takes place only on the 
posterior side of the gemmiparous region, which is also more 
extensive. In some cases late in the development, a slight an- 
terior elevation continues the line of the posterior rim and so 
