and Development of Marsilea. 419. 
at the same time being divided again by a septum directed from 
without inwards towards the common point of contact of all the 
four. By the further elevation of the four upper daughter cells 
the neck of the archegonium is completed. 
At about twenty to twenty-four hours after the escape of the 
spores, the archegonium is ready for impregnation ;- and fer- 
tilization takes place without being limited to any particular 
time of the day*. Beneath the vertex of the central cell a 
portion of colourless mucus separates from its yellowish mass of 
protoplasm, and fills a somewhat lentiform space below the neck 
of the archegonium, which frequently appears to be divided by 
sharp boundary lines from the contracted globular protoplasm. 
This mucus swells, presses upwards, bursts out suddenly with a 
violent explosion between the four pairs of cells of the archego- 
nium, and thus opens the canal of its neck, which then leads 
from without into the interior of the central cell. The mass 
thrown out often remains for days unchanged near the orifice. 
Of the swarming spermatozoids many are usually already at 
hand. They do not seek after the entrance in the mucous en- 
velope of the gynospore, but penetrate it where they come upon 
it. In this process the starch-saccule is an obstacle; by ener- 
getic whirlings they get rid of it, and then swim to the orifice 
of the archegonium, usually with the apex of the screw in 
front, and then, as before, very rapidly, or in the reversed posi- 
tion, and then more slowly. 
Immediately after the expulsion of the mucus, I saw a sper- 
matozoid hasten by, turn the apex of the screw into the orifice, 
turn rapidly upon its axis for a moment, as if it had to overcome 
some internal resistance, and then suddenly disappear in the 
interior of the archegonium, where it was impossible to trace it 
further, on account of the opacity of the prothallium. In one 
case two disappeared, one after the other, in the same archego- 
nium. All subsequent ones were rejected, although no hindrance 
to their admission was observable. 
The number of spermatozoids which collect in the mucous 
envelope of a gynospore often amounts to several hundreds. 
Whole tufts of them adhere by their points to the orifices of the 
fertilized archegonia, the necks of which quickly become brown. 
About the unfecundated specimens those little swarming cor- 
puscles which I formerly mentioned{ soon occur. But I have 
* I have witnessed the swarming of the spermatozoids even about mid- 
night. 
+ The precise observation of the processes of material change within 
the central cell is prevented by the imperfect transparency of the pro- 
thallium. 
{ Monatsber. Berl, Akad. 1862, p. 114. 
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