420 Dv. Hanstein on the Fecundation 



now ascertained, by keeping male and female spores separately, 

 that the })roduction of these is not direetly dependent upon the 

 spores, but that they occur with both kinds, and even with 

 residues from other parts of the fruit of Marsilea. They are 

 Monad-like creatures, which sometimes, like true Monads, swim 

 about briskly, and sometimes, resting, become increased into 

 chain-like series, like certain species of Vibrio. Tlie perfect 

 agreement of their form and mode of occurrence in all observed 

 cases is, however, remarkable; and the singular manner in 

 which both these corpuscles and the spermatozoids crowd toge- 

 ther in front of the orifices of the archegonia induces the belief 

 that the orifice itself may be the seat of some mechanical cause 

 of motion, although this has hitherto escaped direct observation. 



After fecundation, the contents of the central cell contract 

 into a free spheroidal mass, wliich, like the prothallium itself, 

 has a circular transverse section ; by the development of a cell- 

 membrane, this becomes the primitive cell of the germ-plant. 



In about twelve liours the division of this commences by the 

 formation of a wall which is nearly perpendicular, if we regard 

 the longitudinal axis of the macrospore to be placed in an u])- 

 right position. This wall divides it into two somewhat unequal 

 parts, the larger of which becomes developed into the stem, and 

 may therefore be characterized as the anterior portion. Both 

 these parts divide again immediately — the anterioi*, by a hori- 

 zontal wall, into two equal parts, and the posterior, by a parti- 

 tion inclined backwards, into two unequal parts. The germ is 

 now apparently divided almost crosswise into four cells, of which 

 the anterior upper one becomes the first leaf, and the posterior 

 upper one the first root. The anterior lower cell is immediately 

 divided again into two cells by a wall starting from the hori- 

 zontal wall and descending forwards ; the upper of these (now 

 the middle one of the anterior three cells) is the primitive cell 

 of the growing bud. The separated lower cell of the anterior 

 side is developed, in common with the lower posterior cell, into 

 a parenchymatous mass, which, as the so-called /oo^, long retains 

 the young germ-plant in the prothallium and on the gynospore. 

 Each of the three other cells proceeds on its own course of 

 development. 



Three walls, produced one after the other, following the 

 outline of the cell in their position and curvature, and directed 

 towards each other internally, cut ofi" from the primitive root- 

 eell an apical root-cell in contact with the boundary of the germ 

 posteriorly and superiorly; and in this the peripheral side speedily 

 separates, in the form of a cap-like outer cell, from an inner one 

 of a three-sided pyramidal shape. The former is the first cell 

 of the pileorhiza. It first divides crosswise into four contiguous 



