2 7 
Anatomy of the Gernes Selaginella , Spy, 
those of the two later investigators, as may be seen on comparison of 
the following account with the account given by Goebel and Steinbrinck 
(9 and 10 ). 
The type I selected for detailed examination was S. spinosa , since the 
sporangia in this form are large and well thickened, the movements of 
opening the sporangium and ejection of the spores taking place very 
vigorously even in dead sporangia which have been preserved in spirit. 
Schwendener (11) has attributed the function of distribution of the 
spores to the hygroscopic action of the thin inner sporangium wall, and 
states that the outer wall not only takes no part in the shooting of the 
spores, but by its very nature militates against this. Goebel and Stein¬ 
brinck relegate the function to the outer wall. 
The megasporangium is bivalved, and is attached in such a manner 
that one valve (the upper one) faces the axis of the cone, while the lower 
one faces the sporophyll, which is narrowed at the base so as to facilitate 
such movements. The sporangium is four-lobed, the spores being arranged 
so that they fit together in the centre, their inner faces becoming flattened, 
the outer faces remaining rounded, and creating a corresponding bulge 
in the sporangium wall. Two of the spores are situated below in the basal 
portion of the sporangium, two at right angles to these in the upper part. 
I have not as yet seen the alternative arrangement noted by Goebel ( 9 ), 
i. e. one spore lying superiorly and resting on the other three below, and 
therefore judge it to be extremely rare and abnormal. 
In order to examine the various stages in the opening of the mega¬ 
sporangium, I dissected off several sporangia from the strobilus, fastened 
them down by their stalks with thick Canada balsam, so that the valves 
were quite free to move, although bodily movement of the whole was 
prevented, and watched them under a low power. On drying, two cracks 
first of all appear in the region marked c , c (PI. Ill, Fig. 4) ; the apex then 
opens fairly rapidly, though not with a jerk. The cracks divide the 
sporangium into two upper flaps and a basal boat-shaped portion. One of 
the flaps remains practically stationary, the other opens still further, until 
finally the sporangium gapes widely and all the four spores are exposed. 
After a short quiescent period, the four spores are jerked out with great 
violence, frequently to a distance of 10 cm. 
A careful examination of the sequence of events shows quite clearly 
that the essential and functional part in the ejection of all four spores is the 
basal boat-shaped portion, and not the flaps (see Goebel and Steinbrinck), 
and the explanation is to be found in the extremely complicated nature of 
the outer wall of the sporangium. In PI. Ill, Fig. 4, a sketch is given of the 
lower valve of the sporangium of S', spinosa. The crack regions can easily 
be distinguished before opening occurs, for the cells in the dehiscing region 
are small and shallow, standing out in sharp contrast with the much 
