326. = Structural and Physiological Botany. 
contents of this apical papilla, which is enclosed in the gela’ 
tinous envelope that surrounds the whole spore, divide, 
when the spore begins to germinate, into a central cell and 
several superficial ones. The latter become filled with 
chlorophyll, and grow into a body which is placed like a 
cap on the apex of the macrospore, and then form the’cells 
Fig. 449.--Marsilea salvatrix; 1.a macrcspore before fertilisation with its mucila- 
ginous envelope,; the pro- -embryo i is developed from the roundish papilla g at the 
apex of the spherical spore (x 15); 6 microspores (x 15), c single microspore 
(x 100) ; 11. antherozoid with its attached vesicle (x 690); ILI. pro-embryo with 
oospore seen in transverse section ; the spherical oospore a has already a cell-wall 
(x 200); IV. young plant seven days later still attached to the spore A(x 7) 
(all after Hanstein). 
which immediately surround the central cell, and which 
therefore constitute the archegonium. At the proper time 
one or more antherozoids force themselves through the neck 
of this archegonium, and presumably disappear in the in- 
terior of the central cell, ze in an oosphere. ‘The oospore 
or fertihsed oosphere then becomes surrounded by a cell- 
wall (Fig. 449 111., 0), divides ito new cells, and gradually — 
grows into a new plant (Fig. 449 I1v.). In their alternation 
ee 
