MORPHOLOGY 
rangia below. There is also a swelling tissue which in this case bursts 
out at the top of the sporocarp. The remarkable longevity and 
resisting power of the sporocarps of Marsilea deserve mention. Sporo- 
carps preserved on herbarium sheets for fifty years and others kept in 
95 per cent alcohol have resumed activity when placed in water. 
In contrasting the structures called sporocarps in Salviniaceae and 
Marsileaceae, it is evident that they are very different. In Salviniaceae 
413 
FIGS. 412-414. Male gametophyte of Marsilea: 412, first division of the microspore 
into vegetative cell (the smaller) and antheridium initial; 413, first division of an- 
theridium initial; 414, antheridium with wall of sterile cells investing spermatogenous 
cells (shaded). After CAMPBELL. 
the sporocarp is an indusium investing a sorus, while in Marsileaceae 
it is a leaf blade inclosing a group of sori with their indusia. 
Gametophytes. The male gametophyte does not emerge from the 
microspore, as it does in Salviniaceae, remaining entirely within the spore 
coat, as in Selaginella and Isoetes. As in all the previously mentioned 
cases of heterospory, a single vegetative cell 
and a single antheridium make up the male 
gametophyte (figs. 412-414) ; but in Marsile- 
aceae the output of sperms is 32, much larger 
than in Salviniaceae (8) and in Isoetes (4). The 
sperms of Marsilea are remarkable for the 
great number of coils in the beak, reaching 
'3 or ,4, the upper or 13 having no cilia 
(fig. 415). The female gametophyte closely 
resembles that of the Salviniaceae, and the nucleus of the great nutritive 
cell remains undivided, as in Salmnia (figs. 416, 417). 
Embryo. The embryo develops as in all the leptosporangiate ferns, 
the first wall of the egg being vertical (parallel with the long axis of the 
archegonium), and the four body regions being differentiated at the quad- 
rant stage. It is noteworthy that the Marsileaceae have retained the 
primary vertical wall of the egg, characteristic of the leptosporangiate 
