1914] PICKETT—PROTHALLIUM OF CAMPTOSORUS 237 
with the germination of the spore, namely, that the first division 
of the cell may produce a second prothallial cell instead of a 
rhizoid. 
Antheridia and archegonia 
The antheridia develop in much the same general way as 
described by Campsett' for Onoclea Struthiopteris as a type of 
the Leptosporangiatae. The stages in development are sug- 
gested in figs. 42-46. The one point worthy of mention is the 
formation of the neck cell. This cell is cut off by a division of the 
initial antheridial cell in a plane parallel to the prothallial surface, 
and is very regularly found, although sometimes the more orthodox 
development shown in fig. 44 is evident. 
The archegonial meristem is but little in evidence, being of 
small area and not conspicuous. It develops on prothallia soon 
aiter the appearance of the antheridia, and is found only on such 
plants as have a well formed apical group. Archegonia are found 
on plants 1.5mm. or more in width. Their development is in 
every way typical of the Leptosporangiatae, but only a few (4-8) 
are found on a prothallium. 
Summary 
The spores of Camptosorus rhizophyllus germinate very irregu- 
larly in point of time. 
Prothallia bearing antheridia only and those bearing both 
antheridia and archegonia are produced. 
Both antheridial and archegonial prothallia show a wide varia- 
Hon in size and form, the result of a promiscuous cell division and 
growt 
_ The formation of a typical V-shaped apical cell is rarely found, 
if at all, and the apical group is usually unsymmetrically placed. 
Old prothallia, bearing both antheridia and archegonia, may 
develop several marginal growing regions, and may even pro- 
duce proliferations capable of independent growth. 
The archegonia follow the typical Leptosporangiatae in their 
* Mosses and ferns, 1905, p. 315. 
