1919.] The Sixth I ndian Science Congress. elxv 
dium cernuum, as well as to the erect assimilating filaments and 
probably also to the walls of the chambers in the Marchantiales 
on the one hand and the leaves of the Jungermanniales on the 
The prothallus of Eqgisetum debile is thus a highly synthetic 
structure showing relationships with several groups. It thus 
p s that the Liverworts are more closely related to 
the Equisetales than to any other group of the Pteridophytes. 
In this connection the reduction shown by the genus Hquisetum 
in its leaves and its vascular system and the presence of spiral 
bands on the walls of its sporangia which are so common in 
the Liverwort capsule-walls are perhaps not without signifi- 
cance. 
I have used the word reduction throughout to indicate the 
process of evolution in the Liverworts, but it should not be 
f 
reproduction implies some modifications in the vegetative 
region. There can hardly beany doubt, for example; that leafy 
Liverworts are still undergoing modifications and producing 
new species by the variations in their leafy shoots. 
This conception of the process of reduction in the Liver- 
palaeontological evidence that whole groups of plants like the 
teridosperms and the Sphenophyllales which flourished in 
allies in later times. (Progressus Rei Botanicae, 1908. gain 
Lady Isabel Browne says: “ Many 
Equisetaceae as the direct descendants of the Calamariae. For 
as pass upwards from the Palaeozoic tree-like Calamites, 
to the older of the Mesozoic Equisitites, which, though still very 
large, were smaller than Calamites, and to the more recent 
species of Equisitites and finally to the living Equisetum we 
trace a steady diminution in size.” (New Phytologist, Vol. IT.) 
To me it appears just what one might expect in many cases. 
During the evolution of the Vegetable Kingdom the forms 
