3 22 
Shiv Ram Kashyap. 
The most important feature of this plant, however, is that both 
the male and the female receptacles are terminal at first and not 
dorsal outgrowths as in other species of Plagiochasma. After the 
receptacles have been laid down growth stops for some time but is 
later continued by an adventitious apical shoot (Pig. 8). The plant 
in this respect behaves in the same way as Preissia commutata} 
The plant has invariably a jointed appearance. The new adventitious 
shoot sometimes remains very small, hardly more than a small 
process. Usually, however, it grows for some time and produces a 
second receptacle. Even a third receptacle may be formed in this 
way. The stalk of the carpocephalum, which is about 3 mm. long, 
is more or less sulcate on all sides, but there is a deeper groove 
always on the anterior side though it has no rhizoids (Pig. 6, e). 
The base of the receptacle has only small scales. 
It has been mentioned before that the stalk of the carpocephalum 
in Stephensoniella brevipedunculata is very small and has a very shallow 
groove containing only a few rhizoids. This condition is correlated 
with the continued forward growth of the thallus. In P. articulatum 
we have another stage of reduction where the rhizoids have been 
altogether suppressed and the forward growth begins even earlier 
than in Stephensoniella after the formation of the female receptacle. 
In other species of Plagiochasma there is never any stoppage of 
growth and the carpocephalum appears to be purely dorsal from 
the very beginning. Two other considerations point to the same 
conclusion. (1) In some of the higher Marchantiales, e.g., 
Marchantia , both the thallus and the receptacle possess barrel-like 
pores. In other genera, e.g., Reboulia, both the male and female 
receptacles have barrel-like pores while the thallus has ordinary 
simple pores. 2 In Plagiochasma only the female receptacle has 
barrel-shaped pores while the male receptacle and the thallus have 
simple pores. The barrel-shaped pores have persisted in the sexual 
receptacles while they have become reduced in the thallus to simple 
pores. (2) It is simpler to suppose that the scales surrounding the 
sexual receptacles of plants like Plagiochasma represent the ventral 
scales of a branch system than to suppose that they have arisen as 
such from the dorsal side which ordinarily does not possess them. 
It will be seen from the above description of P. articulatum 
that the stalk of Plagiochasma is homologous with the stalk of the 
receptacle of the Composite and is not a structure which has arisen 
independently. 
* Cavers, “ Contributions to the biology of the Hepaticae. Part I.— 
Targionici, Reboulia, Preissia, Monoclea." Leeds and London, 1904. 
J Cavers, “ Inter-relationships of the Bryophyta,” Figs. 21-23. 
