558 Transactions. 
Conceptacles—Durvillaea is dioecious, male and female conceptacles 
being found on different plants. The conceptacles are flask-shaped cavities 
(fig. 12), opening to the exterior by a narrow mouth, or ostiole. The con- 
ceptacle itself extends down into the medullary tissue, which is specially 
differentiated around it, forming a layer of two or three cells in thickness, 
composed of elongated cells tapering at both ends and dovetailing into one 
another. The structure of the conceptacle does not differ much in the male 
and female plants. 
The apical cell, by division of which the conceptacles arise, does not 
persist as in Splachnidium, und there are no hairs protruding from the 
ostiole. The cells lining the cavity grow out into short papillae just near 
the mouth, the shortest being found nearest the exterior. Both male and 
n t 
branched hairs (d), and the oogonia (o) are borne on both, or may be sub- 
sessile. Hooker (1864) found them to be subsessile, and in one specimen 
oogonium is also rich in food material in the form of small round bodies. 
. 
transversely, the middle portion again dividing into two longitudinally, 
| у 2 
Jacquinot (1845), and he called the four resulting oospheres “ tetraspores. 
It was first rightly interpreted by Kutzing in his examination of Sarco- 
рћусиз potatorum (Phyco. Mem., p. 38). The four oospheres, surrounded 
: t 
plant by rupture of the wall at the apex, and leave the empty oogonium 
still attached to the wall of the conceptacle. 
ogonia in all stages of development may be found in the same con- 
ceptacle. The colourless globular bodies were found in one in which the 
ripe dark-brown oospheres were being expelled. From this it would seem 
that the conceptacles are able to produce oogonia indefinitely by the con- 
tinued activity of the cells lining the cavity. Mr. 
В. М. Laing (1885) states , 
