THE 
NEW PHYTOhOGIST. 
Vol. XIV, Nos. 4 & 5. April & May, 1915. 
- [Published June 7th, 1915.] 
STRUCTURE AND DEVELOPMENT OF 
TARGIONIA HYPOPHYLLA. 
By Lillian O’Keeffe, B.Sc. 
[With Two Figures in the Text.] 
I. Introduction. 
A LTHOUGH a good deal has been published on the morphology 
of the interesting liverwort Targionia hypophylla, there are 
certain points which have not been covered in previous descriptions 
and others concerning which conflicting statements have been made 
by different investigators. The object of this paper is to give a 
brief statement of some of the results obtained in an examination of 
this plant. The material used was chiefly collected near Teignmouth, 
South Devon, by Dr. Cavers, who suggested the investigation and 
placed at my disposal not only a large supply of plants but also 
preparations made by himself when investigating the structure and 
biology of Targionia (3). 
II. Growing-point and Development of Air-chambers. 
In his general account of the apical growth of the thallus in 
the Marchantiacese, Leitgeb (9, p. 2) simply states that in this group, 
as in the Ricciaceae, growth is effected by a transverse row of initial 
cells, the number of these varying with the width of the groove in 
which the growing point is situated. The only accounts of apical 
growth in Targionia are those given by Cavers (3) and by Deutsch 
(6), the former writer stating that there is “ a short transverse row 
of initial-cells lying almost in the plane of the ventral surface of the 
thallus,” while Deutsch states that “ the thallus is formed by the 
segmentation of a single, cuneate apical cell, cutting off segments on 
four faces ” and that “ relative to the apical cells found in the other 
genera of the Marchantiales, the apical cell of Targionia is rather 
small.” It is obvious that the exact structure of the growing-point 
