420 Dr. Hanstein on the Fecundation 
now ascertained, by keeping male and female spores separately, 
that the production of these is not directly 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 Pot Vibrio. The 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, which, 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 hours 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 up- 
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 anterior, 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 foot, 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 thei position and curvature, and directed 
towards each cther internally, cut off from the primitive root- 
cell 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 
