1913] PETRY—PROTOCORM OF OPHIOGLOSSUM 163 
procambium strands figured, when traced through the serial sec- 
tions, are found to connect. They constitute the vascular strand 
which closes the gap of the leaf second in order from the apical 
cell; the procambium of a trace which will supply the youngest 
leaf connects with it. 
12 
Fics. 12, 13.—Fig. 12, longitudinal section through apical region of rhizome; 
236; Fig. 13, longitudinal section through apical region of rhizome: #,p, procam- 
bium strands; x 236. 
Discussion 
In view of the complex anatomy of the specimen investigated, 
it seems necessary to state that the term “protocorm” is used by 
Lanp (11) and in this paper without any intended implication 
that the object so named is necessarily simple in its structure. 
The name has been applied rather with reference to its external 
appearance, which is not unlike that of mature plants of Phyllo- 
glossum and of young plants of Lycopodium cernuum, to which 
the name was first applied. 
In order to compare the vascular system of the protocorm with 
that of an ordinary rhizome of the species, the effects of the unusual 
behavior of the segments of the apical cell must be taken into 
account. By reason of the eversion produced, the tissue surround- 
__ ing the central pit corresponds directly to the cortex of an ordinary 
_ thizome. In the same way, as regards origin, the tissue immedi- 
